Sunan an-Nasa'i 5406
سنن النسائي#5406SahihIt was narrated that 'Abdur-Rahman bin Abi Bakrah said:"My father wrote to 'Ubaidullah bin Abi Bakrah - who was the judge of Sijistan - saying: 'Do not pass judgment between two people when you are angry, for I heard the Messenger of Allah [SAW] say: No one should pass judgment between two people when he is angry
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih - Agreed Upon
In-book reference: 49:28