Narrated Ibn `Aun:I wrote a letter to Nafi` and Nafi` wrote in reply to my letter that the Prophet (ﷺ) had suddenly attacked Bani Mustaliq without warning while they were heedless and their cattle were being watered at the places of water. Their fighting men were killed and their women and children were taken as captives; the Prophet (ﷺ) got Juwairiya on that day. Nafi` said that Ibn `Umar had told him the above narration and that Ibn `Umar was in that army.
حَدَّثَنَا عَلِيُّ بْنُ الْحَسَنِ، أَخْبَرَنَا عَبْدُ اللَّهِ، أَخْبَرَنَا ابْنُ عَوْنٍ، قَالَ كَتَبْتُ إِلَى نَافِعٍ فَكَتَبَ إِلَىَّ أَنَّ النَّبِيَّ صلى الله عليه وسلم أَغَارَ عَلَى بَنِي الْمُصْطَلِقِ وَهُمْ غَارُّونَ وَأَنْعَامُهُمْ تُسْقَى عَلَى الْمَاءِ، فَقَتَلَ مُقَاتِلَتَهُمْ، وَسَبَى ذَرَارِيَّهُمْ، وَأَصَابَ يَوْمَئِذٍ جُوَيْرِيَةَ. حَدَّثَنِي بِهِ عَبْدُ اللَّهِ بْنُ عُمَرَ، وَكَانَ فِي ذَلِكَ الْجَيْشِ.
Bukhari
Manumission of Slaves • Hadith 24