Musnad Ahmad 26:557

Waki’ and Abu Mu’awiyah narrated to us, they said: Al-A’mash narrated to us, from Abu Wa’il, who said: ‘Abdullah said: It is as if I am looking at the Messenger of Allah, may Allah bless him and grant him peace, while he was telling the story of a prophet from among the prophets whom his people had struck, and he was wiping the blood—Abu Mu’awiyah said: he was wiping the blood—from his forehead, and saying: "My Lord, forgive my people, for they do not know."