Matthew 5:32 and 19:9 restore the exception of “unchastity,” perhaps because Joseph was planning to divorce Mary for this reason (Matthew 1:19). The prohibition of divorce was probably also instituted by the Dead Sea sect (Damascus Document 4:20–5:2); see John J. Collins, “Marriage, Divorce, and Family in Second Temple Judaism,” in Leo G. Perdue, et al., Families in Ancient Israel (Louisville, KY: Westminster John Knox Press, 1997), p. 129.