Sahih Muslim , Book 32, Hadith 80 (In-Book) ⓘ
It has been narrated on the authority of Hisham (who learnt it from his father) that the Messenger of Allah said (to Sa'd): You have adjudged their case with the judgment of God. 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 " .
also referenced under: Hadith 1769 (Reference) & Book 19, Hadith 4371 (USC-MSA)