Zavim 1:5-6

Zavim 1:5

If a man had one emission that was as large as three, taking as long as walking from Gad Yon to Shiloach, which is the time it would take to immerse and to dry oneself twice, he’s a full zav. If he had one emission that was as large as two, he renders unclean things on which he lies or sits and he must immerse in running water, but he need not bring an offering. Rabbi Yosi said that the Sages only mentioned “one as large as” in the context of being as large as three (i.e., “one as large as two” is no different from one).

Zavim 1:6

Let’s say that a man had one emission by the day and another at twilight, or he had one at twilight and another the next day. If it’s known that part of the emission happened on one day and part happened the next, then he’s certain when it comes to bringing an offering and ritual impurity. If it’s in doubt whether part happened on one day and part happened the next, then he’s certain when it comes to ritual impurity but in doubt when it comes to the offering. If he had emissions on two different days at twilight, then he’s in doubt both when it comes to ritual impurity and when it comes to the offering. If he had only one emission at twilight, then he’s in doubt vis-à-vis ritual impurity.