Masechet Eduyot, Perek Vav, Mishnah Aleph. The Mishnah says that Rabbi Yehuda ben Bava testified about five different matters.
The first one talks about the laws of mi'un (refusal). If a girl’s father died while she was underage, under 12 years old, then technically she could not be married off by her brothers or her mother. Her father was the only one who had the legal right to marry her off. So she would have to remain unmarried until she was 12 years old. But Hachamim (Sages) said that if we leave her like that, people are going to take advantage of her while she’s a young girl. So they wanted to make sure that, on a rabbinic level, her brothers or mother had the ability to marry her off. As part of that decree, they gave the young girl the ability to opt out of the marriage, to reject it later through mi'un (refusal to stay in the marriage). Even without a get (divorce document), she’s allowed to leave the marriage.
Rabbi Yehuda ben Bava says that there are times when we encourage an underage girl to do mi'un, to declare that she doesn’t want to stay married to her husband, dissolve the marriage, and end it with no get. The reason we would encourage it, even though generally we try to keep them together, is that there are situations where there’s a mitzvah (commandment) that needs to get done. Let’s say, for example, she was married to a man, and that man then has to go do yibum (levirate marriage) with this young girl’s older sister. Yibum is a deoraita (of Torah law) obligation, but you can’t do yibum if the man was already married to her sister. So in that case, we tell the young girl, “Do mi'un, end the marriage,” and then her ex-husband can go do yibum properly with her sister. Those are types of situations where we would encourage the breaking up of this marriage and the promotion of the girl doing mi'un.
Number two tells us that we allow a woman to get remarried to somebody else if her husband went overseas and died there, and we have one witness telling us that he died. Normally, when it comes to two types of testimony about divorce or marriage, we need a minimum of two witnesses. But here, since it was overseas and we don’t think we’re ever going to have that second witness show up, we don’t want to leave this woman agunah for the rest of her life, a chained woman who doesn’t have the ability to end her previous marriage when in reality her husband is probably dead. So Hachamim said that even in this situation, we’re going to allow one witness to testify because we’re nervous we’re never going to find a second witness, since it was in a far-off land.
In the third case, he also testified that a rooster was once stoned in Yerushalayim because the rooster killed somebody. We only have the Pesukim (verses) telling us about an ox: if an ox kills somebody, then we kill that ox. What Rabbi Yehuda ben Bava is telling us is that the law also applies to other animals, not only to an ox.
We’ll also now mention another law about how old wine has to be in order for it to be used on the Mizbeach (altar) as a wine libation. The Torah tells us that the wine poured on the Mizbeach has to be intoxicating, that it has to be a type of wine that isn’t grape juice and has to be fermented for a certain amount of time. He also gave us testimony that wine that was 40 years old was poured as a libation on the Mizbeach in the Beit HaMikdash. That tells us even 40 days of fermenting is enough to call it wine, and it’s not grape juice anymore; therefore, it can be poured on the Mizbeach.
The fifth case is that, even though normally it was done earlier in the morning, it was once brought in the fourth hour of the day. So we learn from here that the Korban Tamid could be offered until the end of the fourth hour, but not later than that.