Deuteronomy 21:11-15

and you see among the captives a beautiful woman, and are strongly attracted to her and would take her as a wife for yourself,

then you shall bring her into your home, and she shall shave her head and trim her nails.

She shall also remove the clothes of her captivity and shall remain in your house, and weep for her father and mother a full month; and after that you may have relations with her and become her husband and she shall be your wife.

But it shall be, if you are not pleased with her, then you shall let her go wherever she wishes; and you certainly shall not sell her for money, you shall not treat her as merchandise, since you have humiliated her.

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