Mishkat al-Masabih 3170
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.
وَعَنْ أَبِي سَعِيدٍ الْخُدْرِيُّ: أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَوْمَ حُنَيْنٍ بَعَثَ جَيْشًا إِلَى أَوْطَاسٍ فَلَقُوا عَدُوًّا فَقَاتَلُوهُمْ فَظَهَرُوا عَلَيْهِمْ وَأَصَابُوا لَهُمْ سَبَايَا فَكَأَنَّ نَاسًا مِنْ أَصْحَابِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ تَحَرَّجُوا مِنْ غِشْيَانِهِنَّ مِنْ أَجْلِ أَزْوَاجِهِنَّ مِنَ الْمُشْرِكِينَ فَأَنْزَلَ اللَّهُ تَعَالَى فِي ذَلِكَ (وَالْمُحْصَنَاتُ مِنَ النِّسَاء إِلَّا مَا ملكت أَيْمَانكُم)
أَيْ فَهُنَّ لَهُمْ حَلَالٌ إِذَا انْقَضَتْ عِدَّتُهُنَّ. رَوَاهُ مُسلم