Abu Sa'id al-Khudri said

At the battle of Hunain God’s Messenger sent an army to Autas, and they met an enemy and fought with them. . Having prevailed over them and taken captives the Prophet’s companions seemed to hold back from having intercourse with them because of their husbands among the polytheists. Then God most high sent down regarding that, “And women already married, except those whom your right hands possess” (Al-Qur’an 4:24). That means that they were lawful for them when their ‘idda* period came to an end. * The period which a widow or divorced woman must observe before remarriage. See Ch. 26. Muslim transmitted it.