Musnad Ahmad 851:1

Hashim narrated to us, Yunus bin Ubayd narrated to us, from Abd Rabbih al-Hujaymi, from Jabir bin Sulaym, or Sulaym bin Jabir, who said: I came to the Prophet, peace and blessings of Allah be upon him, and he was sitting with his companions. He said: I said, "Which of you is the Prophet?" He said: Either he gestured toward himself, or the people pointed to him. He said: He was sitting with his legs drawn up to his abdomen, wrapped in a cloak, the fringe of which had fallen onto his feet. He said: I said, "O Messenger of Allah, I am ignorant of some things, so teach me." He said: "Fear Allah, and do not belittle anything of good, even if it is to pour from your bucket into the vessel of one seeking water. And beware of vanity, for Allah does not love vanity. And if a man insults you and shames you for something he knows about you, do not shame him for something you know about him; thus, the reward will be yours, and the sin will be upon him. And do not insult anyone."