The "Unknown Days" of the Jewish Calendar
This coming week, an unsuspecting person wishing to catch a minyan, who walks into a random shul in many places around the world, might be in for a surprise. After the Shemoneh Esrei prayer on Sunday there will be no Tachanun. On Monday there will be Selichos; and on Thursday there again won’t be Tachanun! Why would this be? No Tachanun generally signifies that it is a festive day; yet, no other observances are readily noticeable. As for the reciting of Selichos on Monday, they are usually reserved for a fast day; yet no one seems to be fasting! What is going on?
The answer is that three separate specific “Unknown Days” happen to fall out during this apparently chock-full week.
Sunday, the 14th of Iyar, is dubbed ‘Pesach Sheini’, which commemorates the day when those who were unable to bring the annual Korban Pesach (special Pesach sacrifice - Pascal lamb) at its proper time (Erev Pesach), were given a second chance to offer this unique Korban. Although technically not considered a real holiday, and despite the fact that it is (astonishingly!) not listed in the traditional Halachic sources as one of the days that Tachanun is not said, nevertheless, the custom for many is not to say Tachanun on Pesach Sheini in order to ‘tap into’ the merit that this particular day had during the times of the Beis HaMikdash. Although the Pri Megadim maintains that Tachanun should be said on Pesach Sheini as the original day it is commemorating was meant only for individuals in unique circumstances, and its absence of mention in the traditional Halachic sources as one of the days that Tachanun is not recited speaks volumes, nevertheless, most authorities rule that one should not say Tachanun on this day.
There is an interesting common custom associated with Pesach Sheini - eating Matzah; but that is not noticeable in shul! Another interesting fact about Pesach Sheini is that it is commonly considered the Yahrtzeit of Rabi Meir Ba’al HaNeis and many visit his grave in Teveria on that day.
This coming Monday will be the third and final day of a semi-annual period that many do not even realize exists: a series of “Days of Tefilla” colloquially known as BeHa”B. This acronym stands for Monday (Beis - 2nd day of the week), Thursday (Hei - 5th day of the week), and the following Monday (Beis). These days are observed on the first Monday, Thursday, and Monday following the earliest Rosh Chodesh after Pesach (Rosh Chodesh Iyar), and likewise after Sukkos (Rosh Chodesh Cheshvan).
The custom of utilizing these specific days for prayer and supplication was already mentioned almost 900 years ago by the Baalei Tosafos, its importance reiterated by the Tur, and unbeknownst to many, actually codified in halacha by the Shulchan Aruch as a proper minhag!
Whose Minhag Is It, Anyway?
Although both the Tur and Rema call BeHa”B a German-French custom, and the Shulchan Gavoah (cited l’maaseh by the Kaf Hachaim) writes that this was not the minhag in Spain, implying that Sefardim are not beholden to keep BeHa”B, nevertheless, it must be noted that the Shulchan Aruch himself must have felt strongly about this minhag of BeHa”B, as aside for spending a whole siman on it
(Orach Chaim 492), he also refers to it and its importance in at least two other locations – Orach Chaim 429: 2 and 566: 2 - 4.
Later Sefardic authorities as well, including the Knesses HaGedolah, Pri Chadash and Chida (ad loc.) also discuss its importance. Therefore, this author finds it interesting that the general Sefardic minhag is not to recite BeHa”B. In fact, the Siman referring to BeHa”B (Orach Chaim 492) is noticeably absent from the Yalkut Yosef Kitzur Shulchan Aruch, implying that it is not relevant to the average Sefardi.
And it is not just the general Sefardi populace who do not say BeHa”B. Already in his time, the Taz noted that even among Ashkenazic communities BeHa”B observance was not widespread. More recently, Rav Menashe Klein, in a side point to the issue being addressed in a teshuva, maintains that one who does not observe BeHa”B is not considered “Poresh Min HaTzibbur” (separating himself from the general community), as even nowadays its observance is not prevalent. But, among many Yeshiva communities, and especially in Eretz Yisrael, reciting BeHa”B twice a year is de rigueur.
The reason most commonly mentioned by the Poskimwhy these days of prayer are following the holidays of Pesach and Sukkos is that over the extended holidays, when there is a mitzvah of feasting and simcha, it is more likely that people may have stumbled in some area due to improper behavior and inadvertent sin, and BeHa”B is meant to help rectify any possible offense. This idea is based on Iyov (Ch. 1: verse 5) who would bring Korbanos after “Y’mei Mishteh”, or “Days of Feasting”. These sins might be due to a variety of probable offenses including: mingling - at a festive meal or even at a Drasha in the Shul (!), Yom Tov and Chol Hamoed related transgressions, Chilul Hashem, or overabundance of merriment and gastronomical pleasures.
Other explanations offered to explain why BeHa”B was established include:
- To entreat Hashem to strengthen our bodies especially at the time of changing seasons when many are likely to get sick.
- To beseech Hashem that we should have abundant harvests after Pesach and plentiful rains after Sukkos.
- To commemorate Queen Esther’s original 3-day fast (which actually was Pesach time, and not Purim time). This is pushed off until the first opportunity after Chodesh Nissan. [The Ta’anis Esther that we fast before Purim is not really due to Esther’s actual fast as recorded in the Megillah, but rather to commemorate that when the Jews went to war against the anti-Semites of their day, they fasted.]
Yet, interestingly, although BeHa”B is traditionally meant to be a fast day, still, very few actually do fast, as in our generations people are considered weaker. Instead, we make do with Selichos (and perhaps Divrei Mussar), with the majority also reciting Avinu Malkeinu. This rationale is found in many sefarim, including the Chavos Yair, Aruch Hashulchan, Mishna Berura, and Kaf Hachaim, who cites this as the Minhag of Prague.
This certainly holds true with BeHa”B, as it is based on a minhag and not an actual biblical source. That is why our fellow walking in would not likely see any other traditional signs of a fast day.
Monday, Thursday, Prayer Days…
Monday and Thursday are considered especially potent days for prayer, as Moshe Rabbeinu climbed Har Sinai to receive the Torah on a Thursday and returned with it on a Monday. A mnemonic to showcase this is the first pasuk read on a public fast day Haftara (Yeshaya Ch. 55: verse 6) “Dirshu Hashem B’H imatzo” - “Seek out Hashem when He is to be found”. The letters Beis and Hei show that an auspicious time when Hashem may be found is on Monday and Thursday; therefore Mondays and Thursdays are preferable for fasting and prayer. For whichever reason BeHa”B was established, we certainly shouldn’t let this golden opportunity for tefillah pass us by.
The third of these ‘Unknown Days’ with no other obvious observances during davening, except the omission of Tachanun on Thursday, is Lag B’Omer [18th of Iyar]. There are several reasons offered for why Tachanun is not said on Lag B’Omer, including:
- It is the day when Rabbi Akiva’s 24,000 students stopped dying.
- It is the day when the Mann (manna) started to fall, feeding Bnei Yisrael in the Midbar.
- It is the day when Rabi Shimon bar Yochai and his son Rabi Elazar came out of the cave they hid in for 13 years.
- It is Rabi Shimon bar Yochai’s Yahrtzeit. However, it is important to note that this understanding might actually be based on a simple printing mistake, and many authorities including the Chida and Ben Ish Chai, maintain that Lag B’Omer is not truly hisYahrtzeit.
- It is the day when Rabi Akiva gave Semicha to his five new students (including Rabi Shimon bar Yochai) after the 24,000 died, allowing the Torah’s mesorah to continue.
- It is the day when Rabi Shimon bar Yochai’s hidden Torah, the Zohar, became revealed to the world.
In Eretz Yisrael, this quasi-holiday is widely celebrated, with over half-a million people converging on the sleepy mountaintop town of Meron to daven, and dance at the grave of Rabi Shimon Bar Yochai, as well as thousands visiting the grave of Shimon HaTzaddik in Yerushalayim.
With enormous bonfires (mostly built by neighborhood children!) seemingly on almost every street corner, Lag B’Omer in Eretz Yisrael has since also become a pyromaniac’s delight and the firefighters’ and asthmatics’ nightmare.
Other locales have a different sort of custom, such as the one in Krakow, Poland to visit the illustrious Rema’s grave on Lag B’Omer, as it is his Yahrtzeit as well. Yet, in most of Chu”tz La’aretz, there is no other real commemoration or observances of this special day, unless one counts the “traditional” game of baseball and subsequent barbeque. So it is quite possible that our clueless colleague might just wonder about the omission of Tachanun on Lag B’Omer.
Hopefully, by showcasing these relatively “Unknown Days”, this article should help raise awareness and appreciation of them and their customs. Incredibly, as we are climbing upwards in this unique time period of Sefiras HaOmer, in anticipation of Kabbalas HaTorah, Hashem has given us an opportunity to observe a few special Yemei Tefilla. May we be zocheh to utilize them to their utmost!
This article was written l’zechus for Shira Yaffa bas Rochel Miriam v’chol yotzei chalatzeha for a yeshua teikif umiyad.
For any questions, comments or for the full Mareh Mekomos / sources, please email the author: firstname.lastname@example.org.
Rabbi Yehuda Spitz serves as the Sho’el U' Meishiv and Rosh Chabura of the
Ohr Lagolah Halacha Kollel at Yeshivas Ohr Somayach in Yerushalayim. He also writes a contemporary halacha column for the Ohr Somayach website titled
“Insights Into Halacha”: http://ohr.edu/this_week/insights_into_halacha/.
 See Sefer HaToda’ah (vol. 2, pg. 253) who explains that it is called this as it is the Pesach that falls out in the second month of the year - Iyar. In the Mishna and Gemara (ex. Rosh Hashana 18a) it is referred to as “Pesach Kattan” or “Pesach Ze’ira” (the Small Pesach).
 Bamidbar (Beha’aloscha Ch. 9: verses 1 – 15). See Rashi (ad loc. verse 10) and Sefer HaChinuch (Mitzva 380).
 The Aruch Hashulchan (O.C. 131: 12) writes that he is astounded that Pesach Sheini is not listed by any of the traditional Halachic sources [including the Gemara, Rambam, Tur, Shulchan Aruch, or even the Mishna Berura!] as one of the days that Tachanun is not said. However, see Shu”t Mor V’Ohalos (Mahadura Kama 39, Ohel Brachos V’Hoda’os, pg. 37 s.v. ode) who posits that there was no reason to list Pesach Sheini as a day with no Tachanun recited, as it is mentioned explicitly in the Torah (meaning it is obvious that there is no Tachanun)! On the other hand, see Shu”t M’Mayanei Yeshua (3) who posits (and explains at length) that this machlokes (between the Pri Chadash and Pri Megadim et al.; see next footnote at length) is based on whether or not a “Chag l’Yechidim” would be enough to exempt the tzibbur from Tachanun. He also discusses the differences between Pesach Sheini and Shavuos in regard to reciting Tachanun the week after. See also the Chida’s Moreh B’Etzba (Ch. 8: 222) who states that on Pesach Sheini one should be “yarbeh simcha ketzas, ki kadosh hayom”.
 These Poskim include (O.C. 131, ad loc.) the Knesses HaGedolah (Haghos on Beis Yosef 12, citing ‘Minhag Salonika’; however, see Magen Giborim ad loc. 18 who states that the minhag of Eretz Yisrael, Mitzraim and Salonika is to say Tachanun on Pesach Sheini), Pri Chadash (7), Elyah Rabbah (14), Ya’avetz (in his Siddur Beis Yaakov vol. 2, Shaar HaYesod, Seder Chodesh Iyar pg. 103, 21), Shalmei Tzibur (10), Sha’arei Teshuva (19), Beis David (Shu”t 53; cited by the Shaarei Teshuva ibid. and Kaf Hachaim ad loc. 99, who explains that there is no real machlokes regarding minhag Salonika, Mitzraim and Eretz Yisrael, but rather that all agree that Tachanun is not said on the 14th of Iyar as it is the true Pesach Sheini, and those who maintained that it was not recited were actually referring to the 15th of Iyar), Yosef Daas and Yad Shaul (Y”D 401), Chida (Machazik Bracha, 5), Butchatcher Rav (Eshel Avraham s.v. nohagin), Maharsham (Daas Torah 7), Shaarei Ephraim (Ch. 10: 27), Shulchan HaTahor (8), Birchas HaPesach (Ch. 16: 5), Aruch Hashulchan (12), Kaf Hachaim (99), Sefer Ishei Yisrael (Ch. 43: 11), Rav Yosef Eliyahu Henkin zt”l’s Ezras Torah Luach (5776, pg. 107; ‘yesh nohagin shelo lomar bo Tachanun’), and the Belz D’var Yom B’Yomo Luach (5776, 14th Iyar). This is also the “Minhag Yerushalayim” - see the Tukachinsky Luach and Halichos Shlomo (on Tefilla, Ch. 11: 9 & Moadim vol. 2, Ch. 11: 20). However, it is known that the Chazon Ish and Steipler Gaon did recite Tachanun on Pesach Sheini (sefer Bein Pesach L’Shavuos, in the introduction to the sefer titled ‘Hanhagos HaChazon Ish’ by Rav Chaim Kanievsky; also found at the end of Sefer Imrei Yosher, 25 and cited in Orchos Rabbeinu vol. 1, pg. 68 and new print 5775 vol. 2, pg. 115: 25, and Moadei HaGra”ch 170, pg.79). See also Shu”t Rivevos Efraim (vol. 1: 339 & vol. 258) who explains that Tachanun is recited at the Mincha before Pesach Sheini, even according to the majority opinion that it is not said on Pesach Sheini itself, as opposed to most other ‘Moadim’. [Most poskim agree with this as well - see Luach Eretz Yisroel (Chodesh Iyar), Halichos Shlomo (Moadim vol. 2, Ch. 11, Dvar Halacha 29), and Ishei Yisrael (Ch. 25: 18).] Although not widely followed, there is also an opinion based on the Zohar (Parshas Baha’alosecha, Rayeh Mehemna, pg. 152b) that Tachanun should not be recited for a full 7 days starting from Pesach Sheini [cited in the Shu”t Mor V’Ohalos (ibid.) quoting Rav Mordechai m’Chernobyl and in Shu”t Divrei Yatziv (O.C. vol. 1: 75, 4 s.v. u’lezeh) quoting the Divrei Chaim of Sanz. The Pischa Zuta (Birchas HaPesach Ch. 16, footnote 6) cites a different reason as well, quoting the Maharsha”k in his Imrei Shefer on Parshas Beha’alosecha. He adds that the Likutei Mahariach (quoting the sefer HaYashar V’HaTov) was also a proponent of this minhag].
 Eshel Avraham ibid.
 Pri Megadim (O.C. 131: M.Z. s.v. mah).
 See Birchas HaPesach (Ch. 16, 5 s.v. yesh and footnote 7), Sefer HaToda’ah (vol. 2, pg. 253), Shu”t Divrei Yisrael (vol. 1: 130), Shu”t Rivevos Efraim (vol. 2: 129, 39 & vol. 3, 331), Orchos Rabbeinu (vol. 2, pg. 97, 17), Nitei Gavriel (Pesach vol. 3, pg. 330), Shu”t Divrei Shalom (vol. 4: 87), Shu”t Kinyan Torah B’Halacha (vol. 7: 42, 3), Halichos Even Yisrael (pg. 218: 3), and the Belz D’var Yom B’Yomo Luach (5776, 14th Iyar). See also Moadei HaGra”ch (164 - 169, ppg. 77 - 79), as well as the maamar in Kovetz Moriah (vol. 397 - 399, Nissan 5775), by its author, Rabbi Matisyahu Gabai, who explains why the Steipler Gaon would eat Matzah on Pesach Sheini, while his brother-in-law, the Chazon Ish, would not.
 Although this is widely assumed and cited by many, nevertheless, see Shu”t Yaskil Avdi (vol. 5: 54, 1) citing the Sdei Chemed (vol. 1, Asifas Dinim, Ma’areches Eretz Yisrael pg. 4a) that the reason masses visit Rabi Meir Ba’al HaNeis’s kever on Pesach Sheini is that the Beis Knesses and Beis Midrash built over his kever in Teverya were inaugurated on Pesach Sheini and many were kavua a minhag to celebrate every year on that day at his kever, similar to Rabi Shimon bar Yochai’s kever on Lag B’Omer. The Sdei Chemed cites several parallels including celebrating their hidden Torah being revealed to the world (‘ohr ha’meir l’olam, u’meir eini chachamim b’halacha’). Additionally, like Rav Shimon, Rav Meir was one of the five new students of Rabi Akiva who received semicha at that time. It is interesting to note that they do not mention Lag B’Omer being the actual Yahrtzeit of Rabi Shimon bar Yochai (see footnote 28), nor Pesach Sheini the Yahrtzeit of Rabi Meir Ba’al HaNeis. In fact, the Ben Ish Chai (Year 1, Parshas Vayeishev 28) mentions the minhag to light a candle ‘l’ilui nishmas’ Rabi Meir Ba’al HaNeis on Rosh Chodesh Teves, implying that that is his true Yahrtzeit. On an interesting side point, there are some who posit [see Rabbi Reuvein Margoliyus’s ‘Lechaker Shemos V’Kinuyim B’Talmud’ (pg. 25: 30, Erech R’ Meir Ba’al HaNeis) at length] that Rabi Meir Ba’al HaNeis is not actually the Tanna Rabi Meir, as we do not find that he was called that name in the Gemara, and it was not until somewhat recently when it was assumed that they are one and the same. In fact, there are two different graves found in Eretz Yisrael, one listed as Rabi Meir (in Teverya; actually two - in separate buildings near each other) and another as Rabi Meir Ba’al HaNeis (in Gush Chalav). Rabbi Margoliyus further (and fascinatingly) opines that the famous Tzedaka in the name of Rabi Meir Ba’al HaNeis is actually based on an erroneous assumption of seeing the “Kupas Ramba”n” established by the great Rishon, the Ramban, when he moved to Eretz Yisrael following his victory in public debate with the apostate Jew-turned Franciscan monk Pablo Christiani. In fact, the Ramban himself wrote (see Toldos Ramban Ch. 4: 13) that he established a yeshiva and a fund to elicit support for it from Jews in Chutz La’aretz. Accordingly, the initials Ramba”n, actually referring to Ra bbi M oshe B en N achman, were mistakenly attributed to Ra bi M eir Ba’al HaN eis.
 Tosafos (Kedushin 81a s.v. sakva), Tur and Shulchan Aruch (O.C. 492: 1). Actually, a BeHa”B of sorts is mentioned even further back, in Maseches Sofrim (Ch. 21: 1- 3), but that seems to be for one specific reason: to commemorate Mordechai and Esther’s three-day fast. See footnote 17. There is an interesting machlokes Rishonim between the Rosh (Taanis Ch. 1: 20) and Mordechai (Taanis, 629) whether BeHa”B is considered a Taanis Yachid or Taanis Tzibbur.
 Shulchan Gavoah (O.C. 492: 1, cited in Kaf Hachaim 492: 8). This is additionally mentioned in the Sefer HaToda’ah (vol. 1, pg 157) and Kitzur Shulchan Aruch of Rav R.B. Toledano (vol. 4: 330).
 Taz (O.C. 566, 3), Shu”t Mishna Halachos (vol. 3: 15, s.v. u’lfa”d). See also Shu”t Igros Moshe (O.C. vol. 1: 106) for an interesting discussion why the Tefilla “Mevorchin BeHa”B” is still recited the Shabbos prior to BeHa”B even when a chosson is present.
 See Rosh (Taanis Ch. 1: 20), Mordechai (Taanis 629), Tur (O.C. 492), Rema (ad loc), Magen Avraham (ad loc, 1), Shulchan Aruch HaRav (ad loc, 1), Mishna Berura (ad loc, 1) and Shaarei Efraim (Ch. 10: 46).
 Mingling at a festive meal or even at a Drasha in the Shul (!) is cited by Rashi & Tosafos (Kiddushin 81a s.v. sakva); Yom Tov and Chol Hamoed related transgressions by the Elyah Rabba (O.C. 492: 3, citing the Ma’aglei Tzedek); Chilul Hashem by the Tur (O.C. 429: 2); overabundance of merriment by the Maharil (Dinei Hayamim Bein Pesach L’Shavuos); and gastronomical pleasures by the Kol Bo.
 See Levush (O.C. 492: 1).
 See Ra’avyah (Taanis 863), Mordechai (Taanis 629), Shach (Y”D 220: 31 s.v. v’nirah li), and Sefer HaToda’ah (vol. 1, pg. 156).
 Maseches Sofrim (Ch. 21: 1 - 3). See also Sefer Minhagei Yisrael (vol. 1, Ch. 26) who opines that, according to this reasoning, the reason for the BeHa”B after Sukkos is not for the same reason as the BeHa”B after Pesach. The Ta’anis Esther that we fast before Purim is not really due to Esther’s actual fast as recorded in the Megillah, but rather to commemorate that when the Jews went to war against the anti-Semites of their day, they fasted (see Mishna Berura 686: 2, quoting the Rambam - Hilchos Taanis Ch. 5: 5)].
 Shu”t Chavos Yair (126), Aruch Hashulchan (O.C. 492: 2), Mishna Berura (566: 6), Kaf Hachaim (O.C. 566: 37; citing the Elyah Rabba quoting the minhag in Prague), Shu”t Mishna Halachos (vol. 9: 174), and Nitei Gavriel (Pesach vol. 3, pg. 242). In a similar vein, see also Shu”t Noda B’Yehuda (Kamma O.C. 35, s.v. hinei), Shulchan Aruch HaRav (Iggeres HaTeshuva Ch. 3, based on the Yerushalmi Nedarim Ch. 8: 1), and Orchos Rabbeinu (vol. 2, pg. 160, Hilchos Taanis 2). See also Rav Yosef Eliyahu Henkin zt”l’s Ezras Torah Luach (5776; pg. 57 and 106), who adds that since the vast majority of people are not actually fasting, one should replace the word ‘Ta’anis’ in the Selichos with ‘Tefilla’ instead. The Belz D’var Yom B’Yomo Luach (5776, Iyar, Be”HaB) adds that the Minhag of the Belzer Rebbes is to at least not serve meat on these days.
 See Midrash Tanchuma (Parshas Vayera 16), Tosafos Bava Kamma (82b s.v. kday shelo), and Mishna Berura (134: 6).
 Matteh Moshe (748). See also Shulchan Aruch (O.C. 580: 3, based on Tosefta (Taanis Ch. 2: 5) and Tur, Shulchan Aruch and Rema (O.C. 134: 1) that Mondays and Thursdays are preferable for fasting and prayer. There is even a minhag of fasting every Monday and Thursday for the ‘Churban HaBayis, on the Torah that was burnt, and for Chilul Hashem’. See also Kaf Hachaim (O.C. 580: 32), who concludes this topic stating that the ikar is that there should be Torah along with Teshuvah, and to be ‘laasok tamid b’Toras Chaim’.
 The Sha’arei Teshuva (492: 1) cites the Ra’avad (Tamim Dayim 177) who maintains that “Yechidim and Anshei Ma’aseh” should keep a BeHa”B after Shavuos as well; yet concludes that the prevailing custom is not to. See also Ra’avyah (Taanis 863), Mordechai (Taanis 629), Beis Yosef (end O.C. 429), Chok Yaakov (492: 1), Shulchan Aruch HaRav (O.C. 492, 1), Magen Avraham (ad loc 1), Levush (ad loc 1), Pri Megadim (E.A. ad loc 1), Chida (Birkei Yosef ad loc 1), Kaf Hachaim (ad loc 1) and Mishna Berura (ad loc 1), who all rule that there is no BeHa”B after Shavuos. Apparently, Zeman Mattan Torah affords less opportunity for nichshal.
 See Tur/ Shulchan Aruch and Rema and relevant commentaries to O.C. (131: 6, and 493: 2).
There are many sefarim available who give full treatment to the topic of Lag B’Omer, including Bein Pesach L’Shavuos and Nitei Gavriel (Pesach vol. 3). It is also worthwhile to read Rabbi Eliezer Brodt’s excellent articles on topic: http://seforim.blogspot.co.il/2011/05/printing-mistake-and-mysterious-origins.html and http://seforim.blogspot.co.il/2008/05/lag-ba-omer-and-upsherins-in-recent.html, and featured in Ami Magazine # 22, as well as the introduction and first chapter to Rabbi Mordechai Zev Trenk’s recent and fascinating ‘Treasures: Illuminating Insights on Esoteric Torah Topics’.
 See Meiri (Yevamos 62b), Sefer HaManhig (citing the Baal HaMaor), Biur HaGr”a (O.C. 131: 6 s.v. b’Lag), Pri Chadash (O.C. 493), Pri Megadim (O.C. 493: M.Z. 1), Shelah (Pesachim 525), Kitzur Shulchan Aruch (120: 6), and Mishna Berura (493: 8).
 See Shu”t Chasam Sofer (Y”D 233 s.v. amnam yada’ati) and Toras Moshe (Parshas Bechukosai, Drush for Chevra Kadisha, pg. 62b).
 See Aruch Hashulchan (O.C. 493: 7).
 See Chayei Adam (vol. 2: 131, 11), Birkei Yosef (O.C. 493: 4), Aruch Hashulchan (ibid.), Kaf Hachaim (ad loc. 27), and Sefer HaToda’ah (vol. 2, pg. 256 and 257). The Sefer HaToda’ah cites that Rav Ovadia M’Bartenura wrote a letter to his brother in1488 stating that the 18th of Iyar is a Yahrtzeit and was celebrated by masses coming and lighting giant torches. However, it seems unclear whether he was referring to Rabi Shimon bar Yochai or Hillel and Shammai, as there was an old minhag to visit their Kevarim near Meron in Iyar.
 See the Chida's Shu”t Maris Ha’ayin (Likutim 7: 8) and Shiyurei Bracha (O.C. 493: 1, Din 2), where he recanted his opinion (Birkei Yosef ibid.) about Lag B’Omer being Rashbi’s Yahrtzeit, and instead maintaining that the celebrations are for different reasons. This is also cited in the Ben Ish Chai's Shu”t Rav Pe'alim (vol. 1: O.C. beg. 11 s.v. Teshuva), and Rav Yaakov Hillel’s ‘Eid HaGal HaZeh’ at length. They maintain that the first mention of Lag B’Omer being Rabi Shimon bar Yochai’s Yahrtzeit is essentially a printing mistake, and only found in a certain version of Rav Chaim Vital’s Pri Eitz Chaim and not in his authoritative Shaar HaKavannos, which actually lists other reasons for the celebrations. Accordingly, the text of Rav Chaim Vital’s was truly ‘Yom Sameach Rabi Shimon Bar Yochai’, and not ‘Yom Shemeis Rabi Shimon Bar Yochai’. See also Orchos Rabbeinu (new edition 5775; vol. 2 pg. 114 - 115: 19 and 22) for more on why Lag B’Omer is a festive day.
 See Yalkut Me’am Loez (Parshas Emor) and Sdei Chemed (Ma'areches Eretz Yisrael 6); the Pri Chadash (ibid.) and Chida (Tuv Ayin 17, 493 and Shiyurei Bracha ibid.) write that it is the day when Rabi Akiva started teaching his five new talmidim.
 See Zohar (Parshas Ha’azinu, Adra Zutra 241), that on the day of Rav Shimon’s petirah, he revealed his hidden Torah which was ‘nismalei ohr gadol shel simcha’. Additionally, the sun did not set until Rav Shimon finished, after which he passed away. See also Bnei Yissaschar (vol. 1, Ma’amarei Chodesh Iyar, Maamar 3: 2, 3, 6 & 7) who explains that this is the reason why the minhag is to “light neiros u'me'oros' on this holy day”. As mentioned in footnote 27, Rav Ovadiah M’Bartenura attested to this minhag being followed already in his time. The Bnei Yissaschar elaborates further on this minhag, citing several other reasons. Additionally, he posits that Lag B'Omer is also the Rashb”i's birthday. See also Orchos Rabbeinu (new edition 5775; vol. 2 pg. 114: 19).
 As per the custom mentioned by Rav Chaim Vital in Sha’ar HaKavannos (pg. 87a; however he interestingly concludes that it is unclear to him whether or not the Arizal had attained his mastery of chochma and Kabbala when he made this historic pilgrimage); see Ateres Zkainim (O.C. 493: 1), Aruch Hashulchan (O.C. 493: 7), and Kaf Hachaim (O.C. 493: 26). However, it must be noted that there were several authorities who were skeptical at best about this custom, including the Chasam Sofer (Shu”t Y”D 233 s.v. amnam yada’ati and Toras Moshe, Parshas Emor, Hesped for the tragic Earthquake in Tzfas, s.v. ach; he actually maintains that the masses going to Meron on Lag B’Omer were part of the cause of this cataclysm) and the Shoel U’Meishiv (Shu”t vol. 5: 39). [See also Shu”t Shaim Aryeh (O.C. 14) who attempts to answer their criticism.] See also Rav Ovadia Yosef zt”l’s Shu”t Yabia Omer (vol. 5: O.C. 35) and Shu”t Yechaveh Daas (vol. 5: 35), where he wrote very strongly against going up to Meron on Lag B’Omer. It is also well known that many Rabbanim, including Rav Yosef Shalom Elyashiv zt”l, when asked whether one should go to Meron on Lag B’Omer, replied “Rabi Shimon is duh”, pointing to a Gemara (see, for example, Ashrei HaIsh O.C. vol. 3: pg. 432, 17). In other words, if one wants to celebrate Rabi Shimon bar Yochai’s greatness properly on “his day”, they feel that it is preferable to sit and learn his Torah (i.e. learn Gemara). His son-in-law, Rav Chaim Kenievsky, echoed the same sentiments (see Teshuvos HaGra”ch vol. 2, pg. 744 and Moadei HaGra”ch 173, pg. 81). In fact, the Chida (Moreh B’Etzba Ch. 8: 223) mentions such a minhag as well. For a discussion as to the level of Rabi Shimon bar Yochai’s greatness, see Rabbeinu Chananel’s commentary to Sukkah (45b) and Shu”t Rav Pe’alim (vol. 1, Y”D 56 s.v. v’hu pg. 72a) on why he specifically was the one to be zocheh to reveal the Zohar.
 See sefer Bein Pesach L’Shavuos (pg. 302).
Disclaimer: This is not a comprehensive guide, rather a brief summary to raise awareness of the issues. In any real case one should ask a competent Halachic authority.
L'iluy Nishmas the Rosh HaYeshiva - Rav Chonoh Menachem Mendel ben R' Yechezkel Shraga, Rav Yaakov Yeshaya ben R' Boruch Yehuda, and l'zchus for Shira Yaffa bas Rochel Miriam and her children for a yeshua teikef u'miyad!