Leviticus 20:20-22

²⁰And if a man lie with his aunt, he hath uncovered his uncle's nakedness: their sin shall they bear: they shall die childless.

²¹And if a man take his brother's wife, it is an unclean thing: he hath uncovered his brother's nakedness: they shall be childless.

²²And ye shall observe all my statutes, and all mine ordinances, and do them, that the land whither I bring you to dwell therein vomit you not out.