Sahih
Muslim
صحيح مسلم
32
The Book of Jihad and Expeditions
كتاب الجهاد والسير
Chapter 22: Permissibility of fighting those who break a treaty; Permissibility of letting besieged people surrender, subject to the judgement of a just person who is qualified to pass judgement
باب جَوَازِ قِتَالِ مَنْ نَقَضَ الْعَهْدَ وَجَوَازِ إِنْزَالِ أَهْلِ الْحِصْنِ عَلَى حُكْمِ حَاكِمٍ عَدْلٍ أَهْلٍ لِلْحُكْمِ
Sahih Muslim 1769 b
It has been narrated on the authority of Hisham (who learnt it from his father) that the Messenger of Allah (ﷺ) said (to Sa'd)
You have adjudged their case with the judgment of Allah. the Exalted and Glorified.وَحَدَّثَنَا أَبُو كُرَيْبٍ، حَدَّثَنَا ابْنُ نُمَيْرٍ، حَدَّثَنَا هِشَامٌ، قَالَ قَالَ أَبِي فَأُخْبِرْتُ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " لَقَدْ حَكَمْتَ فِيهِمْ بِحُكْمِ اللَّهِ عَزَّ وَجَلَّ " .
Grade: Sahih