Musnad Ahmad 937:282

Hassan ibn Musa narrated to us, Ibn Lahi'ah narrated to us, Darraj narrated to us, from Abu al-Haytham, from Abu Dharr, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Six days, then understand, O Abu Dharr, what I say to you after." When the seventh day came, he said: "I advise you to fear Allah in the secret of your affair and its openness. If you do evil, then do good. Do not ask anyone for anything, even if your whip falls. Do not accept a trust, and do not judge between two people."