Leviticus 18:18

18:18 You must not take a woman in marriage and then marry her sister as a rival wife ¹  while she is still alive, ²  to have sexual intercourse with her.

Matthew 19:5-6

19:5 and said, ‘For this reason a man will leave his father and mother and will be united with his wife, and the two will become one flesh’? ³  19:6 So they are no longer two, but one flesh. Therefore what God has joined together, let no one separate.”

¹ tn Or “as a concubine”; Heb “And a woman to her sister you shall not take to be a second wife [or “to be a concubine”].” According to HALOT 1059 s.v. III צרר, the infinitive “to be a second wife” (לִצְרֹר, litsror) is a denominative verb from II צָרָה A (“concubine; second wife”), which, in turn, derives from II צר “to treat with hostility” (cf. J. E. Hartley, Leviticus [WBC], 283, and B. A. Levine, Leviticus [JPSTC], 122).

² tn Heb “on her in her life.”

³ sn A quotation from Gen 2:24.