Musnad Ahmad 32:1140

Yazid ibn Harun narrated to us, Humayd informed us, from Anas, that the Prophet, peace and blessings of Allah be upon him, was wounded on his face on the day of Uhud, and his incisor tooth was broken, and he was struck with a throw upon his shoulders, so the blood began to flow down his face. He was wiping it from his face while saying: "How can a nation succeed that has done this to their Prophet, while their Prophet calls them to Allah?" Then it was revealed: "Not for you is the decision whether He turns in mercy to them or punishes them" [Al-Imran: 128], until the end of the verse.