The strong one is the one who controls himself

لَيْسَ الشَّدِيدُ بِالصُّرَعَةِ، إِنَّمَا الشَّدِيدُ الَّذِي يَمْلِكُ نَفْسَهُ عِنْدَ الْغَضَبِ

The strong one is not the one who overcomes people by his strength; the strong one is the one who controls himself while in anger.