Menachot 65 - 71
Counting Days and Weeks
Abayei said, “It’s a mitzvah to count days and it’s a mitzvah to count weeks.”
Although regarding the mitzvah of Sefirat Ha’Omer the Torah mentions both seven weeks and (until) fifty days to be counted from the second day of Pesach until the beginning of Shavuot, there is a disagreement on our daf about what we should do nowadays when there is no Beit Hamikdash. Abayei said we should count both days and weeks, as was done at the time of the Beit Hamikdash when the Omer offering was brought on the second day of Pesach. The gemara states that the Rabbis of the Yeshiva of Rav Ashi counted the days and the weeks. This is a proof to the opinion of Abayei.
However, the gemara also states that the Sage Ameimar counted the days but did not count the weeks. He said, “It (the counting nowadays) is to remember what was done in the Beit Hamikdash. Rashi explains that Ameimar was explaining that the counting done nowadays is not an obligation because there is no Omer offering and we count nowadays only to remember what was done in the Beit Hamikdash. Therefore, counting the days is sufficient.
What is the source of the dispute between Abayei and Ameimar? There are many approaches to explain why they hold different views. One approach is that Abayei rules that the mitzvah of Sefirat Ha’Omer nowadays is a Torah mitzvah and therefore should be fulfilled in the same manner as it was at the time of the Beit Hamikdash — meaning counting both days and weeks. Ameimar, on the other hand, holds that the mitzvah of Sefirat Ha’Omer nowadays is not a Torah mitzvah, but rather a Rabbinical mitzvah. Therefore, the Rabbis decreed to count only the days of the Omer, and this would serve as a reminder of the mitzvah that was fulfilled at the time when the Beit Hamikdash still stood. (Rambam)
Another approach to understand the dispute between Abayei and Ameimar is based on both of these Amoraic Sages agreeing that the mitzvah of Sefirat Ha’Omer nowadays is a Rabbinical mitzvah and not a Torah one. Abayei’s opinion is that in spite of its being Rabbinical nowadays, it should still be fulfilled in the same manner as when it was being fulfilled as a Torah mitzvah in the time of the Beit Hamikdash — counting both days and weeks. Ameimar disagrees with this point and reasons that since it is only a Rabbinical mitzvah nowadays, the Rabbis felt it to be correct and sufficient to count only the number of days without counting the weeks. (Tosefot)
The halacha is to prefer the opinion of Abayei and to count both days and weeks, but to also take into account the opinion of Ameimar as perhaps the correct view. Therefore, one should try to remember to count the days and the weeks each night. And if a person counted the days without the weeks he should count a second time, this time counting the days and the weeks but without a beracha. And even if he forgot to count a second time, mentioning both the days and the weeks, he may continue counting on the rest of the nights with a beracha. In the event that he counted the weeks but not the days (for example on the seventh day of counting he said “Today is one week” without mentioning days at all) according to all opinions he has not fulfilled his obligation for that day.
- Menachot 66a