Moses said. They quote the substance of the law of the levirate (i.e. the brother-in-law) in Deuteronomy 25:5, Deuteronomy 25:6, by which it was enacted that if a married man died without a son, his brother or the next of kin should marry the widow, and the firstborn son of this union should be regarded and registered as the son of the deceased.
This was a law not peculiar to the Hebrews, but prevalent from immemorial times among many ancient peoples, e.g. Persians, Egyptians, and found in force among some nations in modern times, as Arabians, Druses, Cireassians, etc.
It seems not to have been enforced in any case, but to have been left to the good will of the survivor, who might escape the obligation by submitting to a certain social obloquy (Deuteronomy 25:7-10).
The motive of the regulation was the maintenance of a family and the non-alienation of property. Many authorities assert that the law did not apply in the case of a man who left daughters (Numbers 27:8), but only in that of a childless widow.
Later rabbinism limited the obligation to a betrothed woman, not yet actually married. But whatever may have been the limitations allowed in these days, the question of the Sadducees took its stand on the old legal basis, and endeavoured to draw therefrom a ridiculous inference.
Shall marry; ἐπιγαμβρευ ìσει. The verb, found in the Septuagint, is used properly signifying "to take a woman to wife as the husband's kinsman" ( γαμβρο ìς), and generally, "to contract affinity by marriage."
Raise up seed. The firstborn son of such a marriage was the legal heir of the deceased brother, and bore his name. The natural and the legal paternities are seen in the genealogies of our Lord, and occasion some difficulties in adjustment.