مِشْكَاةُ الْمَصَابِيحِ
Mishkat al-Masabih 3731
The Offices of Commander and Qadi
How to Conduct the Office of Qadi, and Fear of it - Section 1
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.)
Mishkat al-Masabih, 3731مُتَّفق عَلَيْهِ (الألباني)