"Also you shall not approach a woman to uncover her nakedness as long as she is in her customary impurity.
Leviticus 18:19
Surrounding context
18:18 Nor shall you take a woman as a rival to her sister, to uncover her nakedness while the other is alive.
18:19 "Also you shall not approach a woman to uncover her nakedness as long as she is in her customary impurity.
18:20 Moreover you shall not lie carnally with your neighbor's wife, to defile yourself with her.