Leviticus 18:8

This is the one case which appears (apart from two others in the imprecations, Deuteronomy 27:22-23), but stated in different words, in Deut. (Deuteronomy 22:30 [Hebrews 23:1], Deuteronomy 27:20). This has been thought to point to the code represented by the v.in Deut. as earlier than that here; but an easier explanation is to suppose that the practice, as specially prevalent at the time, needed specific prohibition. Illicit connexion with a stepmother here forbidden, was not uncommon in the polygamous East. See Driver, Deut., p. 259, for the custom in Syria and Arabia. It seems to have been still common in the time of Ezekiel (Ezekiel 22:10).