Deuteronomy 21:10-17

10“When you go out to battle against your enemies, and the Lord your God hands them over to you and you lead them away captive,

11and you see a beautiful woman among the captives, and desire her and would take her as your wife,

12then you shall bring her [home] to your house, and she shall shave her head and trim her nails [in preparation for mourning].

13She shall take off the clothes of her captivity and remain in your house, and weep (mourn) for her father and her mother a full month. After that you may go in to her and be her husband and she shall be your wife.

14But it shall be that if you have no delight and take no pleasure in her, then you shall let her go wherever she wishes. You certainly shall not sell her for money; you shall not deal with her as a slave or mistreat her, because you have humbled her [by forced marriage].

15“If a man has two wives, one loved and the other unloved, and both the loved and the unloved have born him sons, and the firstborn son belongs to the unloved wife,

16then on the day when he wills his possessions to his sons, he cannot treat the son of his loved wife as firstborn in place of the son of the unloved wife—the [actual] firstborn.

17Instead he shall acknowledge the son of the unloved as the firstborn, by giving him a double portion of all that he has, for he was the beginning of his strength (generative power); to him belongs the right of the firstborn.