Leviticus 18:15

Thou shalt not uncover the nakedness of thy daughter in law: she is thy son’s wife; thou shalt not uncover her nakedness.

Cross-reference

Leviticus 20:12 repeats the prohibition against sex with a daughter-in-law and adds the death penalty.

Genesis 38:18 records Judah having sex with his daughter-in-law Tamar — a specific instance of the prohibited act in Leviticus 18:15.

Ezekiel 22:11 lists defiling a daughter-in-law among Israel's sins — directly echoing the prohibition in Leviticus 18:15.

Amos 2:7 Parallel

In Amos 2:7, the prophet condemns a man and his father going to the same young woman — the very incest prohibited here, showing Israel's lawlessness.