Leviticus 20:10-12

10If a man has sex with another man's wife you must kill him and the woman.

11A man is sinning if he has sex with his father's wife. You must kill the man and the woman. They have destroyed the father's honour. Their sin causes their death.

12A man is sinning if he has sex with his son's wife. You must kill them both. They have done a strange thing. Their own sin causes their death.