كتاب المغازى
64  
Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
(30)
Chapter: The return of the Prophet (saws) from Ahzab and his going out to Bani Quraiza
(30)
بَابُ مَرْجَعِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مِنَ الأَحْزَابِ وَمَخْرَجِهِ إِلَى بَنِي قُرَيْظَةَ وَمُحَاصَرَتِهِ إِيَّاهُمْ
Sahih al-Bukhari 4121

Narrated Abu Sa`id Al-Khudri:

The people of (Banu) Quraiza agreed to accept the verdict of Sa`d bin Mu`adh. So the Prophet (ﷺ) sent for Sa`d, and the latter came (riding) a donkey and when he approached the Mosque, the Prophet (ﷺ) said to the Ansar, "Get up for your chief or for the best among you." Then the Prophet (ﷺ) said (to Sa`d)." These (i.e. Banu Quraiza) have agreed to accept your verdict." Sa`d said, "Kill their (men) warriors and take their offspring as captives, "On that the Prophet (ﷺ) said, "You have judged according to Allah's Judgment," or said, "according to the King's judgment."

حَدَّثَنِي مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا غُنْدَرٌ، حَدَّثَنَا شُعْبَةُ، عَنْ سَعْدٍ، قَالَ سَمِعْتُ أَبَا أُمَامَةَ، قَالَ سَمِعْتُ أَبَا سَعِيدٍ الْخُدْرِيَّ ـ رضى الله عنه ـ يَقُولُ نَزَلَ أَهْلُ قُرَيْظَةَ عَلَى حُكْمِ سَعْدِ بْنِ مُعَاذٍ، فَأَرْسَلَ النَّبِيُّ صلى الله عليه وسلم إِلَى سَعْدٍ، فَأَتَى عَلَى حِمَارٍ، فَلَمَّا دَنَا مِنَ الْمَسْجِدِ قَالَ لِلأَنْصَارِ ‏"‏ قُومُوا إِلَى سَيِّدِكُمْ ـ أَوْ ـ خَيْرِكُمْ ‏"‏‏.‏ فَقَالَ ‏"‏ هَؤُلاَءِ نَزَلُوا عَلَى حُكْمِكَ ‏"‏‏.‏ فَقَالَ تَقْتُلُ مُقَاتِلَتَهُمْ وَتَسْبِي ذَرَارِيَّهُمْ‏.‏ قَالَ ‏"‏ قَضَيْتَ بِحُكْمِ اللَّهِ ‏"‏‏.‏ وَرُبَّمَا قَالَ ‏"‏ بِحُكْمِ الْمَلِكِ ‏"‏‏.‏
Reference : Sahih al-Bukhari 4121
In-book reference : Book 64, Hadith 165
USC-MSA web (English) reference : Vol. 5, Book 59, Hadith 447
  (deprecated numbering scheme)