Jami At Tirmidhi
1334
Sahih+3

Abdur-Rahman bin Abi Bakrah narrated:"My father wrote to 'Ubaidullah bin Abi Bakrah who was a judge: "Do not pass a judgement between two people while you are angry, for indeed I heard the Messenger of Allah (ﷺ) saying: 'The judge should not judge between two people while he is angry

SahihAhmad Muhammad Shakir
SahihAl-Albani