1. Rav Nachman bar Yitzchak: The custom follows three elders in three different arguments.
2. The Gemara states that one may pour nine Kav of water on himself to become Tahor after having a nocturnal emission.
3. Rav clarifies the situations in which nine Kav may be used and when nine Kav may not be used.
4. There is a dispute about a person who finds excrement in the place where he has just finished praying.
5. There is a dispute about a person who starts urinating while in the middle of his Shemoneh Esreh.
A BIT MORE
1. One of these is the opinion of Rebbi Ilai that the obligation to give the first shearings from the sheep to a Kohen applies only in Eretz Yisrael.
2. The Gemara notes that some people relied on this leniency, while others did not. Rebbi Yanai said that those who do not rely on it will have a long life.
3. If someone purposely has an emission, he may not use nine Kav to become Tahor. If he is healthy and did not purposely have an emission, he may use nine Kav. If he is sick and did not purposely have an emission, he does not need to immerse at all.
4. Rabah: Even though he sinned, his prayer was valid. Rava: His prayer is considered an abomination, since he should have ensured that there was no excrement in the area before he prayed.
5. Everyone agrees he should stop praying until he has finished urinating. Some say that when he starts again he should start from the beginning of Shemoneh Esreh, and some say he should resume from where he stopped.