Leviticus 18:18-20

New Catholic Bible

¹⁸ You shall not take the sister of your wife while she is still alive, uncovering her nakedness. They would be rivals.

¹⁹ “ ‘You shall not approach a woman to uncover her nakedness during her menstrual impurity. ²⁰ You shall not have sex with your neighbor’s wife, defiling both her and yourself.