Leviticus 20:12, 17

“ ‘If a man has sexual relations with his daughter-in-law, both of them are to be put to death. What they have done is a perversion; their blood will be on their own heads.

“ ‘If a man marries his sister, the daughter of either his father or his mother, and they have sexual relations, it is a disgrace. They are to be publicly removed from their people. He has dishonored his sister and will be held responsible.