Leviticus 15:1-3

And the LORD spake unto Moses and to Aaron, saying, Speak unto the children of Israel, and say unto them, When any man hath a running issue out of his flesh, {because of} his issue he {is} unclean. {running...: or, running of the reins} 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.