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.

Genesis 38:16

38:16 He turned aside to her along the road and said, “Come on! I want to have sex with you.” (He did not realize it was his daughter-in-law.) She asked, “What will you give me in exchange for having sex with you?”

Genesis 38:18

38:18 He said, “What pledge should I give you?” She replied, “Your seal, your cord, and the staff that’s in your hand.” So he gave them to her and had sex with her. She became pregnant by him.

Deuteronomy 27:23

27:23 ‘Cursed is the one who has sexual relations with his mother-in-law.’ Then all the people will say, ‘Amen!’