The Revolution
The Muslims' anger increased because of Uthman's and his rulers' behaviour. The Prophet's Companion's in Madina wrote to people every where:
If you want Jihad, then come to it. Because your Caliph has corrupted Muhammad's religion.
For this reason, the delegates from Kufa, Egypt, Basra, and the like came to Madina and went to the Caliph to ask him to change his based policy. But he dismissed them. So, they went to Ali Bin Abu-Talib, our Master Muhammad's cousin and his successor.
Imam Ali [a] hoped that Uthman would come back to the laws of Islam. Thus he went to advise him:
Don't be a tool in Marwan's hand. Don't let him direct you to whatever he likes. Don't forget your position with respect to Allah's Apostle [s].
Uthman agreed to announce his repentance before people. So, he went out and apologized to people for his bad behaviour. Besides he promised them to follow a new policy Allah and his Apostle accepted. But Marwan, who was cunning, said to him:
Don't be weak before people. Threaten them!
Nayylah, Uthman's wife, knew that Marwan was a bad man and that he disliked Muslims. For this reason, she said to her husband:
Listen to Ali because people love and obey him: don't listen to Marwan because people hate him.
Uthman did not listen to those who advised him. So, people revolted and killed him in his palace.
source : sibtayn