Musnad Abu Ya'la al-Mawsili 160:218

Ahmad ibn Ibrahim al-Dawraqi narrated to us, Safwan narrated to us, from Abdullah ibn Sa'id ibn Abi Hind, from Muhammad ibn Uthman al-Akhnasi, from Sa'id al-Maqburi, from Abu Hurayrah, who said: The Messenger of Allah (peace be upon him) said: "Whoever is appointed as a judge among the people has been slaughtered without a knife."