Leviticus 20:20-22

²⁰If a man sleeps with his aunt, he has dishonored his uncle. They will bear responsibility for their sin, and they will die without children.

²¹If a man marries his brother's wife while his brother is still living, that is disgraceful. He has dishonored his brother, and I will take away from their children any property they may have inherited from their parents.

²²You must therefore keep all my statutes and all my decrees; you must obey them so that the land into which I am bringing you to live will not vomit you up.