Leviticus 15:16-18

“Whenever a man has an emission of semen, he must bathe his entire body in water, and he will remain ceremonially unclean until the next evening. Any clothing or leather with semen on it must be washed in water, and it will remain unclean until evening. After a man and a woman have sexual intercourse, they must each bathe in water, and they will remain unclean until the next evening.