When thou goest forth to war. The same thing is now commanded respecting wives as above respecting meats. As regarded the Canaanites, who were destined and devoted to destruction, we have seen that the Israelites were prohibited from taking their women to wife, lest this connection should be an enticement to sin; but Moses now goes further, viz., that the Israelites, having obtained a victory over other nations, should not marry any of the captive women, unless purified by a solemn rite. This, then, is the sum, that the Israelites should not defile themselves by profane marriages, but in this point also should keep themselves pure and uncorrupt, because they were separated from other people, to be the peculiar people of God. It was better, indeed, that they should altogether abstain from such marriages; yet it was difficult so to restrain their lust as that they should not decline from chastity in the least, degree; and hence we learn how much license conquerors allow themselves in war, so that there is no room for perfect purity in them. Wherefore God so tempers His indulgence as that the Israelites, remembering the adoption wherewith He had honored them, should not disgrace themselves, but in the very fervor of their lust should retain some religious affection. But the question here is not of unlawful ravishment, but Moses only speaks of women who have been made captives by the right of war, for we know that conquerors have abused them with impunity, because they had them under their power and dominion. But since many are led astray by the blandishments of their wives, God applies a remedy, viz., that the abjuration of their former life should precede their marriage; and that none should be allowed to marry a foreign wife until she shall have first renounced her own nation. To this refers the ceremony, that the woman should shave her head, and cut her nails, and change her garments, and lament her father and her family for an entire month, viz., that she may renounce her former life, and pass over to another people. Some of the rabbins twist the words to a different meaning, as if God would extinguish love in the minds of the husbands by disfiguring the women; for the shaving of the head greatly detracts from female beauty and elegance; and "to make the nails," for so the words literally mean, they understand as to let them grow; and the prolongation of the nails has a disgusting appearance. But their gloss is refuted by the context, in which she is commanded to put off the raiment of her captivity.: But I have no doubt but that their month of mourning, their shaven head, and the other signs, are intended by God for their renewal, so that they may accustom themselves to different habits. And with the same object they are commanded to bewail their parents as if dead, that they may bid farewell to their own people. To this the Prophet seems to allude in Psalm 45:10, when he says, "Hearken, O daughter, and consider, and incline thine ear; forget also thine own people, and thy father's house;" for he intimates that otherwise the marriage of a foreign woman with Solomon would not be pure and legitimate, unless she should relinquish her superstitions, and devote herself to God's service. Nor was it needless that God should require the Israelites diligently to beware lest they should take wives as yet aliens from the study of true religion, since experience most abundantly shows how fatal a snare it is. But although we are not now bound to this observance, yet the rule still holds good that men should not rashly ally themselves with women still devoted to wicked superstitions.

The regulations which now follow in the rest of this and throughout the next chapter bring out the sanctity of various personal rights and relations fundamental to human life and society.
Deuteronomy 21:10-14. The war supposed here is one against the neighboring nations after Israel had utterly destroyed the Canaanites (compare Deuteronomy 7:3), and taken possession of their land.

When thou goest forth to war against thine enemies,.... This refers to an arbitrary war, as Jarchi remarks, which they entered into of themselves, of choice, or through being provoked to it by their enemies; and not a war commanded by the Lord, as that against the seven nations of Canaan, and against Amalek; since there were to be no captives in that war, but all were to be destroyed:
and the Lord thy God hath delivered them into thine hands; given them the victory over their enemies, so that they were obliged to surrender themselves to them prisoners of war:
and thou hast taken them captive, or "led his or their captivity (b) captive"; led them captive who used to lead others, denoting their conquest of victorious nations; see a like phrase in Psalm 68:18.
(b) "et captivam duxerit captivitatem ejus", Pagninus, Montanus, Vatablus.

By this law a soldier was allowed to marry his captive, if he pleased. This might take place upon some occasions; but the law does not show any approval of it. It also intimates how binding the laws of justice and honour are in marriage; which is a sacred engagement.

THE TREATMENT OF A CAPTIVE TAKEN TO WIFE. (Deuteronomy 21:10-23)
When thou goest to war . . . and seest among the captives a beautiful woman . . . that thou wouldest have her to thy wife--According to the war customs of all ancient nations, a female captive became the slave of the victor, who had the sole and unchallengeable control of right to her person. Moses improved this existing usage by special regulations on the subject. He enacted that, in the event that her master was captivated by her beauty and contemplated a marriage with her, a month should be allowed to elapse, during which her perturbed feelings might be calmed, her mind reconciled to her altered condition, and she might bewail the loss of her parents, now to her the same as dead. A month was the usual period of mourning with the Jews, and the circumstances mentioned here were the signs of grief--the shaving of the head, the allowing the nails to grow uncut, the putting off her gorgeous dress in which ladies, on the eve of being captured, arrayed themselves to be the more attractive to their captors. The delay was full of humanity and kindness to the female slave, as well as a prudential measure to try the strength of her master's affections. If his love should afterwards cool and he become indifferent to her person, he was not to lord it over her, neither to sell her in the slave market, nor retain her in a subordinate condition in his house; but she was to be free to go where her inclinations led her.

Treatment of a Wife who had been a Prisoner of War. - If an Israelite saw among the captives, who had been brought away in a war against foreign nations, a woman of beautiful figure, and loved her, and took her as his wife, he was to allow her a month's time in his house, to bewail her separation from her home and kindred, and accustom herself to her new condition of life, before he married her. What is said here does not apply to the wars with the Canaanites, who were to be cut off (vid., Deuteronomy 7:3), but, as a comparison of the introductory words in Deuteronomy 21:1 with Deuteronomy 20:1 clearly shows, to the wars which Israel would carry on with surrounding nations after the conquest of Canaan. שׁבי and שׁביה, the captivity, for the captives.

Enemies - Of other nations, but not of the Canaanites.