Leviticus 18:15-18

¹⁵Do not have sex with DOU your daughter-in-law, because she is your son's wife.

¹⁶Do not have sex with your brother's wife, because that would disgrace your brother.

¹⁷Do not have sex with the daughter or granddaughter of any woman whom you have previously had sex with; they are her (OR, your) close relatives. Having sex with any of them would be a wicked thing to do.

¹⁸While your wife is still living, do not marry your wife's sister and have sex with her.