It is narrated from Zuhrah ibn Yazid al-Muradi that a Muslim man had a slave girl who ran away and joined the enemy. (After some time) the Muslims obtained war booty, and the owner of the slave girl recognized her. Hazrat Abu Ubaidah (may Allah be pleased with him) wrote a letter to Hazrat Umar (may Allah be pleased with him) to inquire about the matter. Hazrat Umar (may Allah be pleased with him) wrote: If the khums (one-fifth) of the slave girl has not been taken out and she has not been distributed, then she should be returned to her owner. But if the khums has been taken out and the booty has been distributed, then keep her as she is (she will remain with the one who received her).