In his book on Uthman, Taha Hussain has quoted a letter addressed by Ashtar, the rebel of Kufa, to Uthman. On the strength of this letter, Taha Hussain argues that the rebels did not deny the authority of Uthman; they merely wanted the government to be just and fair.
This letter is quoted hereunder: "From Malik b Harith (Ashtar) to the Caliph who is guilty and blameworthy; who has strayed from the path of the Holy Prophet, and who has neglected the Holy Quran.
We have read your letter. Your rulers should refrain from being tyrannical. They should not exile the citizens. We agree to be loyal to you. You are under the impression that we have acted unjustly. This is your misconception that has hurled you in the precipice, whereby tyranny appears as justice to you, and falsehood looks as the truth to you. Refrain from being unjust to our people; do not exile them from their cities, and do not appoint your favorites as our Governors. Repent before God and appoint Abdullah b Qais, or Abu Musa Asha'ari, or Hudhaifa as our Governor. We are happy with these persons. Save us from your Walid, your Saeed, and other men of your family."
It is very strange that on the basis of this letter. Taha Hussain supports the stand of the rebels, and finds fault with Uthman. This is most unfair and uncharitable. A mere glance at the letter will show that it is coached in most disrespectful language. At the outset, Ashtar has expressed in very strong terms his want of confidence in Uthman by referring to him as guilty, blameworthy, one who has strayed from the right path, and one who has neglected the Quran. Nothing could be more disrespectful to the authority of the Caliph, and after expressing such no-confidence it was preposterous to hold that they were loyal to him. The trend of the letter clearly betrays that the rebels were bent on mischief, and they wanted to create disorder on one pretext or the other.
After reading the above letter I have arrived at the conclusion that the rebels had no real grievance against the Government; they were merely spearheading a subversive movement, at the instance of powers hostile to Islam. Those who raised the bogey of tyranny and injustice on the part of Uthman or his Government were merely playing in the hands of the enemies of Islam.