Sahih Muslim Book 45, Hadith 140
The strong-man is not one who wrestles well but the strong man is one who controls himself when he is in a fit of rage.
This hadith has been narrated on the authority of A'mash with the same chain of transmitters.
I heard Allah's Messenger (ﷺ) as saying: One is not strong because of one's wrestling skillfully. They said: Allah's Messenger, then who is strong? He said: He who controls his anger when he is in a fit of rage.