Abu Bakra wrote to his son who was in Sijistan: 'Do not judge between two persons when you are angry, for I heard the Prophet ﷺ saying, "A judge should not judge between two persons while he is in an angry mood."  

كَتَبَ أَبُو بَكْرَةَ إِلَى ابْنِهِ وَكَانَ بِسِجِسْتَانَ بِأَنْ لاَ تَقْضِيَ بَيْنَ اثْنَيْنِ وَأَنْتَ غَضْبَانُ فَإِنِّي سَمِعْتُ النَّبِيَّ ﷺ يَقُولُ لاَ يَقْضِيَنَّ حَكَمٌ بَيْنَ اثْنَيْنِ وَهْوَ غَضْبَانُ