Musnad Ahmad 1119:30

Yazid narrated to us, he said: Faraj ibn Fudalah informed us, from Rabi'ah ibn Yazid, from Muslim ibn Qurazah, from 'Awf ibn Malik, from the Prophet, peace and blessings of Allah be upon him, who said: "The best of your leaders and the best of your imams are those whom you love and they love you, and you pray for them and they pray for you. And the worst of your leaders and the worst of your imams are those whom you hate and they hate you, and you curse them and they curse you." They said: "O Messenger of Allah, shall we not fight them?" He said: "No, as long as they perform the prayer among you. Beware, whoever has a ruler over him and sees him committing something of the disobedience of Allah, let him dislike what he has done, but do not withdraw a hand from his obedience."