Deuteronomy 21:10-14


10 When you go to fight a battle against your enemies, the Lord your God will give you power over them. You will take some of them as prisoners. 11 You may see among them a beautiful woman that you want to take as your wife. 12 Then you must bring her into your home. She must cut the hair off her head. She must cut her fingernails. 13 She must change the clothes that she was wearing when you found her. Let her live in your house and weep for her parents for a whole month. Then you may have sex with her. You will be her husband and she will be your wife. 14 Later, you may not be pleased with her. If so, you must let her go wherever she wants. You must never sell her or make her become a slave. You must not do that, because you have made her have sex with you, as your wife.

21:12‘Fingernails’ are the hard pieces at the end of a person's fingers.