Musnad Ahmad 826:1

Ibn Numayr narrated to us, Hisham narrated to us, from his father, from al-Ahnaf ibn Qays, from an uncle of his who was called Jariyah ibn Qudamah al-Sa'di, that he asked the Messenger of Allah, peace and blessings of Allah be upon him, and said: "O Messenger of Allah, tell me a statement that will benefit me, and make it brief for me so that I may perhaps comprehend it." The Messenger of Allah, peace and blessings of Allah be upon him, said: "Do not get angry." He repeated the question to him, until he repeated it to him several times, and each time he said: "Do not get angry."