Leviticus 18:17-19

New Revised Standard Version Catholic Edition

¹⁷ You shall not uncover the nakedness of a woman and her daughter, and you shall not take^[a] her son’s daughter or her daughter’s daughter to uncover her nakedness; they are your^[b] flesh; it is depravity. ¹⁸ And you shall not take^[c] a woman as a rival to her sister, uncovering her nakedness while her sister is still alive.

¹⁹ You shall not approach a woman to uncover her nakedness while she is in her menstrual uncleanness.