This uncleanness is from his discharge, whether his body allows the discharge to flow or blocks it. So his discharge will bring about uncleanness.
We have here the law concerning the ceremonial uncleanness that was contracted by running issues in men. It is called in the margin (Lev 15:2) the running of the reins: a very grievous and loathsome disease, which was, usually the effect and consequent of wantonness and uncleanness, and a dissolute course of life, filling men's bones with the sins of their youth, and leaving them...
Commenting on Leviticus 15:1-18
And this shall be his uncleanness in his issue,.... Or the sign of it, by which it may be judged whether he is unclean by it or no: whether his flesh run with his issue; or salivates, or emits a flow of matter like a saliva, or in the manner of spittle: or his flesh be stopped from his issue; with it, or because of...
And this shall be his uncleanness in his issue: whether his flesh run with his issue, or his flesh be stopped from his issue, it [is] his uncleanness. (b) Of the thing of which he shall be unclean.