Deuteronomy 21:11
And seest among the captives a beautiful woman, and hast a desire unto her, that thou wouldest have her to thy wife; And seest among the captives a beautiful woman, and hast a desire unto her, that thou wouldest have her to thy wife;
The verse concerns a woman taken captive from a conquered people whom an Israelite desires to take as his wife, with the fuller guidance for dealing with such captives given in Deuteronomy 21:10-14. The choice is placed within rules requiring her to leave her former religious community before joining an Israelite household. The month of mourning and the rites of shaving her head and paring her nails signified her final separation from her idolatrous kindred and her becoming a proselyte, and only then could she be taken as a wife and treated as one of the people.
The law forbids immoral use of the captive and does not permit using her as a thing of lust, but requires making her his wife. She was reserved for incorporation into an Israelite family, not enslavement, but to be kept and reared in virtue to a life many times better than in her own nation. If the man later rejects her or cannot get along with her, he must let her go free with the standing of an Israelite woman, and may not sell her or treat her as property or as a slave. Some female children among the captives may have been kept to become wives.
This dealing with captives is far better than slavery and in harmony with justice, and much more merciful and humane than the practice in the surrounding lands. It shows a regard for women far above that of all foreign nations, and slaves in Israel were often treated more humanely than free people in surrounding lands. The law was God doing the very best He could with Israel at that time, dealing with a people but little removed from the heathen after the long sojourn in Egypt who could not be brought to see a higher way. He suffered the practice without destroying free will, for He will not force men to be machines and always does the best He can do with every nation, and the very character of the laws shows their origin was divine. The laws given through Moses were so much better than what the heathen around Israel knew that they were as America of a hundred years ago compared to barbarous China or Turkey. They were light and salvation to those in darkness, leading on to still greater light.