Musnad Abu Ya'la al-Mawsili 154:97

Shayban narrated to us, Mu'tamir narrated to us, he said: I heard 'Abd al-Malik ibn Abi Jamilah, from 'Abdullah ibn Mawhab, from Ibn 'Umar, he said: I heard the Prophet, may Allah bless him and grant him peace, saying: "Whoever is a judge and judges with injustice, he is among the people of the Fire. And whoever is a judge and judges out of ignorance, he is among the people of the Fire. And whoever is a judge and judges with justice, it is likely that he will escape evenly [without reward and without sin]."