Imam Ali, the fourth khalifah, in discussing the qualities of a leader said:
"O People! You know that it is not fitting that one who is greedy and parsimonious should attain rule and authority over the honour, lives and incomes of the Muslims, and the laws and ordinances enforced among them, and also leadership of them. Furthermore, he should not be ignorant and unaware of the law, lest in his ignorance he misleads the people. He must not be unjust and harsh, causing people to cease all traffic and dealings with him because of his oppressiveness. Nor must he fear states, so that he seeks the friendship of some and treats others with enmity. He must refrain from accepting bribes when he sits in judgement, so that the rights of men are trampled underfoot and the claimant does not receive his due. He must not leave the Sunnah of the Prophet and the law in abeyance, so that the community falls into misguidance and peril."
Nahjul Balagha, p.50, quoted in Imam Khomeini: Islam and Revolution: Writings and Declarations of Imam Khomeini; edited and annotated by Hamid Algar, Mizan Press, Berkeley, CA, US. 1981. p.67.
Not a hadeeth but may be of use.