Sahih Muslim Book 1, Hadith Number 262.

Chapter : The ruler who is unjust to his subjects deserves punishment of Fire.

Hasan reported: Ubaidullah b. Ziyad went to see Ma’qil b. Yasir and he was ailing. He (‘Ubaidullah) inquired (about his health) to which he (Ma’qil) replied: I am narrating to you a hadith which I avoided narrating to you (before). Verily the Messenger of Allah (may peace be upon him) observed: Allah does not entrust to his bondsman the responsibility of managing the affairs of his subjects and he dies as a dishonest (ruler) but Paradise is forbidden by Allah for such a (ruler). He (Ibn Ziyad) said: Why did you not narrate it to me before this day? He replied: I (in fact) did not narrate it to you as it was not (fit) for me to narrate that to you.