(Mishnah): If during Tefilah (Shemoneh Esreh) one remembered that he is a Ba'al Keri, he does not cease praying. Rather, he shortens (says abridged Berachos).

If one descended to immerse - if he can rise from the water, get dressed and recite [Shma] before sunrise, he rises, dresses and recites. If not, he covers himself in the water and recites;

He may not cover himself [and recite] in bad (smelly) water or Mei ha'Mishreh (water in which flax was soaked, nor may he recite facing urine), until adding water.

How much must one distance from them, and from excrement? Four Amos.

(Gemara): Our Mishnah discusses [one who is praying] b'Rabim, but if he is alone, he ceases, like R. Meir;

However, according to R. Yehudah, even if he is alone, he does not cease.

Limitation: This is when he does not have water to immerse in, but if he has water to immerse, even R. Yehudah agrees that he ceases.

A Choleh (Ba'al Keri; it is a burden for him to immerse) - R. Ami said, if he caused himself (he had Bi'ah), he immerses and dies (i.e. he has no Heter before immersing). If [semen came out] b'Ones, we are not stringent on him.

(R. Chagai citing R. Aba bar Zavdi): In either case, we are not stringent on him.

(Beraisa): If a Choleh had Bi'ah, he needs [to shower in] nine Kabim. If a Bari had Bi'ah, he needs [to immerse in] 40 Sa'im.

If a Choleh [saw Keri] b'Ones, we are not stringent on him. If a Bari [saw Keri] b'Ones, he needs nine Kabim.

(R. Zavdi brei d'R. Yakov bar Zavdi citing R. Yonah): If the spring of a city [where people immerse] is far, he recites Shma, descends, immerses, ascends and prays. If he is chilled (it is hard to immerse until later, when it is warm), they made [the law for him] like when the spring is far.

(Mishnah): If not, he covers himself in the water and recites.

Our Mishnah discusses cloudy water, but if it is clear, it is forbidden. If he can make it cloudy with his feet, he makes it cloudy.

We distance from human excrement four Amos [always], and from dog excrement four Amos, when he puts [dog excrement] into hides (to tan them).

(R. Yirmeyah citing R. Ze'ira): If a Neveilah decayed, one must distance from it four Amos.

Support (R. Avina - Mishnah): How much does one distance from them (bad water, Mei ha'Mishreh, urine), and from excrement? Four Amos. (This shows that one must distance from every foul odor, not only from excrement!)

Rebuttal (R. Ami citing R. Shamai): [Our Mishnah] discusses water in which laundry was soaked (the odor is due to excrement).

Rejection (R. Mana): The Mishnah says, not in bad water or Mei ha'Mishreh! (Rather, it is even if it is not due to excrement. We explained this like CHAREDIM.)