Musnad Ahmad 32:1713

'Affan narrated to us, Hammad narrated to us, Thabit informed us, from Anas, that the Prophet, peace and blessings of Allah be upon him, said on the day of Uhud, while he was wiping the blood from his face and saying: "How can a people prosper who wounded their Prophet and broke his incisor tooth while he was calling them to Allah?" Then Allah, the Almighty and Majestic, revealed: "Not for you is the decision whether He turns in mercy to them or punishes them, for they are indeed wrongdoers." [Al 'Imran: 128]