Leviticus 18:15 prohibits the act for which Leviticus 20:12 prescribes the death penalty—command and punishment directly linked.

Leviticus 18:6 gives the general incest prohibition covering all close relatives—Leviticus 20:12 is a specific case.

Genesis 38:16 narrates Judah unknowingly sleeping with his daughter-in-law Tamar—a narrative example of this sin.

Ezekiel 22:11 explicitly lists defiling a daughter-in-law as one of Jerusalem's abominations—directly echoing this law.

Deuteronomy 27:23 curses lying with a mother-in-law—a different relative but similar incest prohibition in the law.