Leviticus 18:17-19

Good News Translation

^17 (A)Do not have intercourse with the daughter or granddaughter of a woman with whom you have had intercourse; they may be related to you, and that would be incest. ¹⁸ Do not take your wife's sister as one of your wives, as long as your wife is living.

^19 (B)Do not have intercourse with a woman during her monthly period, because she is ritually unclean.