Musannaf Ibn Abi Shayba 13:3028

Abu Bakr narrated to us, he said: Ya'la ibn Mansur narrated to us, from Abdullah ibn Ja'far, from Uthman ibn Muhammad, from al-Maqburi, from Abu Hurayrah, from the Prophet (may Allah bless him and grant him peace), who said: "Whoever is appointed as a judge among the people has been slaughtered without a knife."