Deuteronomy 21:10-14

When you go to war against your enemies and the LORD your God delivers them into your hands and you take captives, if you notice among the captives a beautiful woman and are attracted to her, you may take her as your wife. Bring her into your home and have her shave her head, trim her nails and put aside the clothes she was wearing when captured. After she has lived in your house and mourned her father and mother for a full month, then you may go to her and be her husband and she shall be your wife. If you are not pleased with her, let her go wherever she wishes. You must not sell her or treat her as a slave, since you have dishonored her.