Praise be to Allah,
Hushaym narrated to us from Humayd at-Taweel from Anas ibn Maalik who said,
“On the day of the Battle of Uhud, the [right, lower] lateral incisor of the prophet (PBUH) was broken, and his forehead was wounded [so badly that] blood was streaming down his face. He (PBUH) [wiped the blood off his face] saying, ‘What success can come to a people who cover the face of their Prophet with blood as he calls them to the worship of their Lord?’ It was [in this context that] the following verse was revealed,
‘Not for you [but for Allah] is the decision whether He turns in mercy to them or punishes them; for they are indeed wrongdoers.“‘ [ Soorah al-Imran 3:128]
(Musnad Ahmad, Vol. 3, p. 99. The isnaad of this hadeeth is Saheeh according to the conditions set by al-Bukhaaree and Muslim)
Source:
Thulaathiyyaat Musnad Ahmad ibn Hanbal (may Allah have mercy on him)
Reports of Imaam Ahmad that have only three narrators between him and the Prophet, peace, and blessings be upon him.
Shaykh Muhammad ibn Ahmad ibn Saalim as–Saffaareenee al–Hanbalee ~(1114 –1188 AH)