Musnad Ahmad 32:16

Hashim narrated to us, Humaid al-Tawil informed us, from Anas ibn Malik, that the Prophet, peace and blessings of Allah be upon him, had his incisor tooth broken on the day of Uhud, and his forehead was wounded, until the blood flowed down his face. He said: "How can a people prosper who have done this to their Prophet, while he is calling them to their Lord?" Then this verse was 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].