The Messenger of Allah ﷺ said, "The strong man is not the one who overpowers others in wrestling, but the strong man is the one who controls himself when angry."
حدثنا روح حدثنا مالك عن ابن شهاب عن سعيد بن المسيب
أن رسول الله ﷺ قال ليس الشديد بالصرعة ولكن الشديد الذي يملك نفسه عند الغضب
Its isnad is sahih. Bukhari related it, 8/34, in "Adab," "Being wary of anger," and Muslim, 4/2014, no. 2609, in "Righteousness," "The virtue of one who controls himself," and Malik in "Good character," "What has been said about anger," with its wording, 2/906.