Komentaryo sa Levitico 15:2: Rashi, Ibn Ezra, Rashbam & Sforno

כי יהיה זב WHEN THERE BE A RUNNING ISSUE — One might think if there be a running issue from any portion of his body (e. g., ear, nose) he shall be unclean! Therefore it states מבשרו “from his flesh" (i.e. from some part of his flesh) and not from all parts of his flesh (the prefix מ is a partitive מ). Now, however, that Scripture has made a difference between one part of his flesh and another part of his flesh, I have the right to draw a conclusion: it (the Torah) pronounces uncleanness in a case of a man with a running issue (זב) and it pronounces uncleanness in a particular case of a woman with a running issue (זבה). How is it in the case of a זבה? Through that place in her body where she becomes unclean with a lighter uncleanness, viz., that of a נדה, she also becomes unclean with a more stringent uncleanness i.e. through זיבה, a continuance of the issue beyond the usual period! Similarly the זב: through the place where he becomes unclean with a lighter uncleanness, viz., קרי, (an involuntary emission of semen which makes him unclean only until evening; cf. v. 16), he also becomes unclean through a more stringent uncleanness, viz., זיבה (when he is unclean seven days and must bring a sacrifice; cf. vv. 13 ff. with 16 ff.; from the latter it is evident which part of the body is in question; it follows logically that the same part is here intended) (Sifra, Metzora Parashat Zavim, Section 1 5).

flow as in, “flowing with milk” [Exodus 3:8] — i.e., trickling drops

זב מבשרו, our sages understand this as looking like a mixture of seminal fluid and a discharge which is the result of that organ being diseased.