Rashi on Leviticus 15:32/רש"י על ויקרא ט״ו:ל״ב

1זאת תורת הזב THIS IS THE LAW OF HIM THAT HATH AN ISSUE, i.e. anyone who has but one appearance of flux. And what is his law?

2ואשר תצא ממנו שכבת זרע, he is like him to whom a pollution happened: he is unclean with an uncleanness lasting only till the evening (Sifra, Metzora Parashat Zavim, Chapter 9 8; cf. v. 16).