كتاب الإمارة
33  
The Book on Government
(5)
Chapter: The virtue of a just ruler and the punishment of a tyrant; Encouragement to treat those under one's authority with kindness and the prohibition against causing them hardship
(5)
باب فَضِيلَةِ الإِمَامِ الْعَادِلِ وَعُقُوبَةِ الْجَائِرِ وَالْحَثِّ عَلَى الرِّفْقِ بِالرَّعِيَّةِ وَالنَّهْيِ عَنْ إِدْخَالِ الْمَشَقَّةِ عَلَيْهِمْ
Sahih Muslim 1827

It has been narrated on the authority of 'Abdullah b. `Amr that the Messenger of Allah (ﷺ) said:

"Those who are fair and just will be near to Allah on thrones of light, at the Right Hand of the Most Merciful, Glorified and Exalted is He, and both of His Hands are Right, those who are fair and just in their rulings and towards their families and those who are under their authority."
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَزُهَيْرُ بْنُ حَرْبٍ، وَابْنُ، نُمَيْرٍ قَالُوا حَدَّثَنَا سُفْيَانُ، بْنُ عُيَيْنَةَ عَنْ عَمْرٍو، - يَعْنِي ابْنَ دِينَارٍ - عَنْ عَمْرِو بْنِ أَوْسٍ، عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو، قَالَ ابْنُ نُمَيْرٍ وَأَبُو بَكْرٍ يَبْلُغُ بِهِ النَّبِيَّ صلى الله عليه وسلم وَفِي حَدِيثِ زُهَيْرٍ قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ إِنَّ الْمُقْسِطِينَ عِنْدَ اللَّهِ عَلَى مَنَابِرَ مِنْ نُورٍ عَنْ يَمِينِ الرَّحْمَنِ عَزَّ وَجَلَّ وَكِلْتَا يَدَيْهِ يَمِينٌ الَّذِينَ يَعْدِلُونَ فِي حُكْمِهِمْ وَأَهْلِيهِمْ وَمَا وَلُوا ‏"‏ ‏.‏
Reference : Sahih Muslim 1827
In-book reference : Book 33, Hadith 21
USC-MSA web (English) reference : Book 20, Hadith 4493
  (deprecated numbering scheme)