From the creature of Allah, Ali bin Abi Taalib (a), to people whose anger and enmity was on account of Allah, they got angry when they saw that their land was being run over by people disobedient to Allah, when rights were being crushed and obligations were being ignored and spurned, when tyranny and oppression were the order of the day and every good or bad person and every local resident or outsider had to face them, when goodness and piety were taboos and when nobody cared to keep himself away from vices and sins.
After glorifying Allah and paying homage to the Holy Prophet (s) be it known to you that I am sending towards you a creature of Allah who forsakes rest and sleep during days of danger, who does not fear his enemy in the critical junctures, and who is more severe than burning fire to sinners and vicious people. He is Maalik bin Haarith Mazhiji (Mazhij is a sub-class of Bani Nakha'a). Hear him and obey his commands which you will find to be right and according to true canons of Islam. He is such a sword among the swords of Allah that its sharpness will never get blunt or whose stroke and blow will never be without effect and who will never lose an opportunity. If he orders you to advance against your enemies, then advance; if he commands you to halt then halt because he himself will never advance nor halt and will never give orders to advance, halt or retreat without my consent.
In sending him to you, I have given preference to your needs over those of mine so that he may serve you faithfully and may treat your enemies severely and strongly.