The Book of Jihad and Expeditions
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 " .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 God. the Exalted and Glorified
Noch nicht in deutscher Übersetzung verfügbar, daher auf Englisch.
Aus Sahih Muslim, dessen Überlieferungen die Gelehrten als authentisch annehmen.