Leviticus 18:17-18

18:17 You must not have sexual intercourse with both a woman and her daughter; you must not take as wife either her son’s daughter or her daughter’s daughter to have intercourse with them. They are closely related to her – it is lewdness. 18:18 You must not take a woman in marriage and then marry her sister as a rival wife while she is still alive, to have sexual intercourse with her.