When Uthman became the Caliph, he let Abu Musa Ash'ari continue as the Governor of Basra. He continued to hold this office for three years during the caliphate of Uthman. During the year 647 C.E. there were some disturbances in Fars, and some forces had to be sent there to restore law and order. There was shortage of animals at the time, and addressing the people Abu Musa stressed the virtue of undertaking Jihad on foot. The people were impressed with the preaching of Abu Musa Ash'ari, and they volunteered to undertake Jihad on foot in case there was a shortage of animals.
When on the scheduled date, Abu Musa Ashari came out of his palace to lead the people to battle, he rode on a richly caprisoned horse, and his camp equipage was loaded on forty pack animals. The people flared up at this display of luxury on the part of Abu Musa Ash'ari, and the dichotomy in what he preached and what he practiced. Some of the persons held the reins of the horse of Abu Musa Ash'ari and said: "Alight and walk with us on foot, or furnish us horses as well to ride." That annoyed Abu Musa Ash'ari. Harsh words were exchanged between Abu Musa As~h'ari and some of the persons, and he had some persons lashed for their insolence. The reaction of the people to this act on the part of the Governor was violent. They refused to march to the battlefield under his leadership, who did not practice what he preached.
A deputation representing the people of Basra left for Madina, and there they lodged a complaint before Uthman against the conduct of Abu Musa Ash'ari. The news writer from Basra also sent a report which was not favorable to the Governor. Abu Musa had held the office of the Governor for over six years, and because of the length of the term of office he had come to develop a sort of superiority complex which created a gulf between the people and the Governor. Abu Musa Ashari had grown in years, and was prone to prefer a life of ease. Uthman gave a patient hearing to the deputationists. They pressed the need of deposing Abu Musa Ashari from his office. Uthman after hearing all the complaints against Abu Musa Ash'ari came to the conclusion that he was not guilty of any dishonesty or dereliction of duty. He, however, felt that Abu Musa had held the office for long, and it was in public interest that there should be a change. He asked the deputationists: "In case Abu Musa is removed, whom would you like to be Governor?" They said that any young man in whom the Caliph had confidence would be better than the old Abu Musa Ash'ari. Uthman thereupon passed orders deposing Abu Musa Ashiari form the governorship of Basra, and appointing Abdullah b Aamar in his place.