Yevamot 6 - 12
Sanctuary Major and Minor
When the Torah commanded us to respect the Sanctuary, it did not explicitly define the nature of that respect; theoretically, such respect could include prostrating oneself before the Sanctuary as one would before Hashem. To dispel this notion, the Torah coupled in one passage (Vayikra 19:30) the command to observe Shabbat and to respect the Sanctuary. This is to teach us that just as in regard to Shabbat there is no obligation to show respect by bowing to the day (Rashi since the Torah does not mention "respect" in regard to Shabbat) but rather to the One who commanded us to observe Shabbat, so too the respect required regarding the Sanctuary is not respect for the building, but rather for the One who commanded us regarding the Sanctuary.
But how does one show respect for Hashem through his behavior in the Sanctuary?
Our Sages gave us a number of things we must refrain from doing even on the Temple Mount where the ultimate Sanctuary the Beit Hamikdash stood. This list includes some things, such as the prohibition against wearing shoes, which we do not apply to our "minor sanctuaries" of synagogues. But it also includes not using the Temple Mount as a shortcut for getting from one place to another. This sign of disrespect is prohibited even in regard to a synagogue, and is recorded in Shulchan Aruch (Orach Chaim 151:5).
Using the synagogue as a shortcut, or entering it for the purpose of calling someone there to come out, is considered disrespectful, as it is an exploitation of a holy place for a personal need. The halacha instructs us to eliminate the disrespect involved in such actions by reading some words of Torah or saying some mishna or halacha before indulging in the personal activity. If a person is not able to thus justify his presence, he should ask a child to recite the Torah passage he has just learned or at least sit down for a few moments, for even sitting in a synagogue is considered a mitzvah as indicated in the passage "Fortunate are those who sit in Your house." (Tehillim 84:5)
- (Yevamot 6b)
Don't Pour Out the Water
One who has water in his cistern should not dispose of it even if he has no need for it, so long as someone else does have a need.
This lesson of consideration, states Rabbi Yosef, was conveyed to us by Rabbi Yehuda Hanasi, the compiler of the Mishna, in a halacha dealing with the laws of yibum and chalitza, which form the main subject of our mesechta. Should a man die childless, his brother is supposed to perform yibum by marrying her. Should he be reluctant to do so, he must perform the act of chalitza that then releases the widow from her bond to the family and enables her to marry someone else.
But not just anyone else. Even though the Torah did not prohibit her marriage to a kohen, the Sages decreed that she may not do so. Her similarity to a divorced woman is so strong that if she would be permitted to a kohen, there is a danger that people may mistakenly extend such a right to a divorcee, who is forbidden to a kohen by Torah law.
A mishna later on (44a) discusses the case of a man who was married to two wives, one of whom was a divorcee from a previous marriage. In the event of his death without children, his brother must perform yibum or chalitza with one of the widows, automatically freeing the other one to marry at will. It is his choice as to which he prefers to make his wife through yibum. But if he chooses to perform chalitza, he is encouraged to do so with the divorcee. Even though this has no ramifications for him, he should take into consideration that by performing chalitza with the one who is eligible to marry a kohen, he thus renders her ineligible, a situation he could have avoided by performing chalitza with the previously ineligible widow.
This is indeed a case of preserving the water for others even if you don't need it yourself.
- (Yevamot 11b)