Abu Hurayrah (may Allah be pleased with him) reported: 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."
One of the Companions (may Allah be pleased with them) asked the Prophet (may Allah's peace and blessings be upon him) to order him with something that would benefit him in this world and in the Hereafter, so he ordered him not to get angry. His advice 'Do not get angry' repels most of people's harms.