Mukhtasar Muslim

It is narrated from Sayyiduna Abu Sa'id Khudri (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) sent an army towards Autas on the day of Hunain. They confronted the enemy, fought them, prevailed over them, and captured their women. Some of the companions of the Messenger of Allah (peace and blessings of Allah be upon him) disliked having relations with them because their husbands, who were polytheists, were still alive. Then Allah the Exalted revealed this verse: "Forbidden are women who are married, except those whom your right hands possess" (An-Nisa: 24), meaning that when their waiting period ('iddah) has passed, they are lawful for you.