Leviticus 15:31

“You are responsible for keeping the People of Israel separate from that which makes them ritually unclean, lest they die in their unclean condition by defiling my Dwelling which is among them.

^32-33 “These are the procedures to follow for a man with a discharge or an emission of semen that makes him unclean, and for a woman in her menstrual period—any man or woman with a discharge and also for a man who sleeps with a woman who is unclean.”