Mishkat al-Masabih 18 The Offices of Commander and Qadi كتاب الإمارة والقضاء 70

عَنْ أَبِي بَكْرَةَ قَالَ سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقُولُ: «لَا يَقْضِيَنَّ حَكَمٌ بَيْنَ اثْنَيْنِ وَهُوَ غَضْبَانُ»

Abu Bakra told that he heard God’s Messenger say, “No judge must give judgment between two people when he is angry.” (Bukhari and Muslim.)