Leviticus 18:15

18:15 You must not have sexual intercourse with your daughter-in-law; she is your son’s wife. You must not have intercourse with her.

Leviticus 20:12

20:12 If a man has sexual intercourse with his daughter-in-law, both of them must be put to death. They have committed perversion; their blood guilt is on themselves.

Leviticus 20:17

20:17 “‘If a man has sexual intercourse with his sister, whether the daughter of his father or his mother, so that he sees her nakedness and she sees his nakedness, it is a disgrace. They must be cut off in the sight of the children of their people. He has exposed his sister’s nakedness; he will bear his punishment for iniquity.