Nahjul Balagha Instruction 26

Given to one of his officers whom he sent for the collection of zakat and charities.

I order him to fear Allah in his secret matters and hidden actions, where there is no witness except He and no one watches save He. I also order him that whatever he does in obedience to Allah openly should not be different from what he does secretly. He whose hidden position is not different from his open position, and whose action is not different from his words, has discharged his obligation and his worship is pure.also order that he should not harass them, should not be harsh on them and not turn away from them because of superiority of official position over them, because they are brethren in faith and help in the recovery of levies.

Certainly, you have a fixed share and a known right in this levy, and there are other sharers who are poor, weak and starving. We shall discharge your rights. So, you should discharge their rights. If you do not do so you will have the largest number of enemies on Judgement Day. How wretched is the man whose enemies in the view of Allah are the needy, the destitute, the beggars, the turned away, the indebted and (penniless) travellers. He who treats the trust lightly and indulges in treachery and does not keep himself and his faith untarnished by it has certainly secured humiliation in this world, and his humiliation and disgrace in the next world will be greater. Surely, the greatest treachery is the treachery against the Muslim community, and the most ugly deceit is the deceit towards the Muslim leaders; and that is an end to the matter.