Leviticus 20:18

18 “If a man has sexual relations with a woman during her menstrual period, both of them must be cut off from the community, for together they have exposed the source of her blood flow.

Leviticus 20:18 In-Context

16 “If a woman presents herself to a male animal to have intercourse with it, she and the animal must both be put to death. You must kill both, for they are guilty of a capital offense.
17 “If a man marries his sister, the daughter of either his father or his mother, and they have sexual relations, it is a shameful disgrace. They must be publicly cut off from the community. Since the man has violated his sister, he will be punished for his sin.
18 “If a man has sexual relations with a woman during her menstrual period, both of them must be cut off from the community, for together they have exposed the source of her blood flow.
19 “Do not have sexual relations with your aunt, whether your mother’s sister or your father’s sister. This would dishonor a close relative. Both parties are guilty and will be punished for their sin.
20 “If a man has sex with his uncle’s wife, he has violated his uncle. Both the man and woman will be punished for their sin, and they will die childless.
Holy Bible. New Living Translation copyright© 1996, 2004, 2007, 2013 by Tyndale House Foundation. Used by permission of Tyndale House Publishers Inc., Carol Stream, Illinois 60188. All rights reserved.