Musnad Ahmad 32:2127

'Affan narrated to us, Hammad narrated to us, Thabit narrated to us, from Anas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) used to visit us. I had a younger brother who had a sparrow (nughayr) he used to play with, and it died. One day, the Prophet (peace and blessings of Allah be upon him) entered and saw him sad. He said: "What is the matter with Abu 'Umayr, that he is sad?" They said: "His sparrow that he used to play with has died, O Messenger of Allah." He said: "O Abu 'Umayr, what did the little sparrow do? O Abu 'Umayr, what did the little sparrow do?"