Abu Musa Ash'ari (Abdullah bin Qays) wrote a letter to Imam Ali (a) from the place where decision of the arbitration took place. Imam Ali (a) wrote to him the following letter in reply. Sayyid bin Yahya Amawi has quoted this letter in his book Al-Maghazi.
Verily there are many people in this world who have forsaken their salvation and in its place they have accepted the pomp and pleasure of worldly life. They are being driven by their unruly and inordinate desires and they work and speak on behalf of these desires only.
This affair has placed me in an awkward position. The people, who have united against me are those who want everything out of this vicious and wicked world for themselves and for their pleasures. They have drawn their swords against me. I am trying to undo the harm they have done but I am afraid lest the problem should become very serious and unresolvable.
You know very well that no one is more desirous of the Unity of Muslims than I and the only thing which I want to achieve by this unity is the Blessings of Allah and my salvation. I shall do what I have resolved to do even though you change the good opinion which you had about me when we last parted. Surely, unfortunate is he who possesses wisdom and acquires experience and yet does not care to make use of either.
I cannot tolerate lies and I cannot bear to see people undoing the good done by Allah through Islam.
Therefore you should give up forming opinion about things which you have not clearly understood or visualized because many people will try their best to influence you with their insinuations.