Deuteronomy 21:15

“If a man have two wives, etc.] Which is supposed, but not approved of, though permitted because of the hardness of men’s hearts; for it was not so from the beginning, when only one man and one woman were created, and joined together in marriage; but as it was connived at, and become customary, a law is made to prevent confusion, and preserve order in families: one beloved and another hated; or less loved, yet continued his wife, and not divorced. Aben Ezra observes, this follows upon the former, because it is there said, that though first he had a desire to her (the captive beautiful woman), yet afterwards had no delight in her: and they have borne him children both, the beloved and the…”

“If a man have two wives, one beloved, and another hated--In the original and all other translations, the words are rendered "have had," referring to events that have already taken place; and that the "had" has, by some mistake, been omitted in our version, seems highly probable from the other verbs being in the past tense--"hers that was hated," not "hers that is hated"; evidently intimating that she (the first wife) was dead at the time referred to. Moses, therefore, does not here legislate upon the case of a man who has two wives at the same time, but on that of a man who has married twice in succession, the second wife after the decease of the first; and there was an obvious necessity for…”

“Moses did not originate the rights of primogeniture (compare Genesis 25:31), but recognized them, since he found them pre-existing in the general social system of the East. Paternal authority could set aside these rights on just grounds Genesis 27:33, but it is forbidden here to do so from mere partiality. return to 'Top of Page'”

“Two wives - This practice, though tolerated, is not hereby made lawful; but only provision is made for the children in this case. Hated - Comparatively, that is, less loved. Deuteronomy 21:19”

“21:15-17 The law required that a firstborn son receive the greater share of his father’s inheritance (see 21:15-16; 2 Kgs 2:9). The custom of giving the firstborn son a double portion is first recorded here but was implied in earlier practice (see Gen 25:31-34; 27:1-4; 48:8-22). • son of his father’s virility: The eldest male child carried this distinction because he proved that the man was capable of siring children, and a boy in particular.”

“two wives: Gen 29:18, Gen 29:20, Gen 29:30, Gen 29:31, Gen 29:33; Sa1 1:4, Sa1 1:5 Deuteronomy 21:16”

“The Right of the first-born. - Whilst the previous law was intended to protect the slave taken in war against the caprice of her Israelitish master, the law which follows is directed against the abuse of paternal authority in favour of a favourite wife. If a man had two wives, of whom one was beloved and the other hated, - as was the case, for example, with Jacob, - and had sons by both his wives, but the first-born by the wife he hated, he was not, when dividing his property as their inheritance, to make the son of the wife he loved the first-born, i.e., was not to give him the inheritance of the first-born, but was to treat the son of the hated wife, who was really the first-born son, as…”