Musnad Ahmad 32:810

Muhammad ibn Ja‘far narrated to us, Shu‘bah narrated to us, from Abu al-Tayyah, who said: I heard Anas ibn Malik say: The Messenger of Allah (peace and blessings of Allah be upon him) used to mingle with us, to the extent that he would say to a brother of mine: "O Abu ‘Umayr, what did the *nughayr* (small bird) do?" He said: And when the prayer time arrived, we would sprinkle a corner of a mat for him, then he would lead us in prayer, and we would form rows behind him. Shu‘bah said: Then Abu al-Tayyah, after he had grown old, said: Then he stood and prayed, and he did not say "we formed rows behind him" nor "he led us in prayer."