a man shall: This is to be understood as referring to the case of a stepmother. A man in his old age may have married a young woman, and on his dying, his son by another, or a former wife, may desire to espouse her; which is here forbidden. Deu 27:20, Lev 18:8, Lev 20:11, 1Co 5:1, 1Co 5:13 discover: Rth 3:9, Eze 16:8