Musnad Ahmad 26:318

'Abd al-Samad narrated to us, Aban narrated to us, 'Asim narrated to us, from Abu Wa'il, from 'Abdullah, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "The people who will receive the severest punishment on the Day of Resurrection are: a man killed by a prophet, or one who killed a prophet, an imam of misguidance, and a mutilator among the mutilators."