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.)

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