Sayyiduna Ma'qil bin Yasar (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) ordered me to judge between my people. I said: I do not know how to judge well. So he (peace and blessings be upon him) said: "Judge between them, for Allah, the Mighty and Majestic, is with the judge as long as he does not deliberately commit injustice."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17674