The judge

Ibn Abu Bakrah reported: My father wrote to Ubaidullah ibn Abu Bakrah who was a judge, saying: Do not pass a judgment between two people while you are angry, for indeed I heard the Messenger of Allah صلى الله عليه وسلم say, “The judge should not judge between two people while he is angry.”
[Sunan At-Tirmidhi, Book of Judgments, Number 1334]

عَنْ عَبْدِ الرَّحْمَنِ بْنِ أَبِي بَكْرَةَ قَالَ  كَتَبَ أَبِي إِلَى عُبَيْدِ اللَّهِ بْنِ أَبِي بَكْرَةَ وَهُوَ قَاضٍ أَنْ لَا تَحْكُمْ بَيْنَ اثْنَيْنِ وَأَنْتَ غَضْبَانُ فَإِنِّي سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقُولُ لَا يَحْكُمْ الْحَاكِمُ بَيْنَ اثْنَيْنِ وَهُوَ غَضْبَانُ

قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ

سنن الترمذي كتاب الأحكام عن رسول الله صلى الله عليه وسلم باب ما جاء لا يقضي القاضي وهو غضبان