Sunan At-Tirmidhi
Hadith #2020
Abu Hurairah narrated that a man came to the Messenger of Allah and said:""Teach me something that is not too much for me so that, perhaps, I may abide by it."" He (S.A.W) said: ""Do not get angry."" He repeated that (the request) a number of times, each time he replied: 'Do not get angry