A man came to the Prophet (may Allah's peace and blessings be upon him) and said: Advise me He replied: Do not get angry. The man repeated that several times and every time he replied: Do not get angry. [Al-Bukhari]

أن رجلًا قال للنبي -صلى الله عليه وآله وسلم-: أوصني، قال لا تَغْضَبْ فردَّدَ مِرارًا، قال لا تَغْضَبْ». (البخاري)