After a few days the rebels returned to Madina again. They said that they had caught a slave of the Caliph who was carrying a letter to the Governor of Egypt asking him to execute the ring leaders of the rebels. The rebels brought this letter to Ali, who took it to Othman. Othman acknowledged that the letter bore his seal, but he denied all knowledge about the contents of the letter. According to one account the letter was in the handwriting of Marwan, Secretary to the Caliph. The letter remained a mystery, but the Caliph undertook to dismiss the officials at fault within three days. No action was taken within the stipulated period, and on the following Friday, Othman addressed the congregation. The Caliph criticized the rebels for having revolted against his authority and held that thereby they had invited the wrath of God, and in the Hereafter they would be doomed to hell. That led to a great uproar. The rebels threw stones at Othman who was wounded and was carried home in an unconscious state. Ali visited the Caliph, and tried to avert the crisis. The crisis deepened and the rebels blockaded the house of the Caliph. The siege lasted for some days. A rumor was circulated that the Caliph has asked the provincial governors to send some troops to Madina. When the rebels came to know that troops might soon arrive in Madina, they broke into the house of the Caliph and assassinated him. That was a tragedy too deep for tears which cast a dismal shadow on the subsequent history of Islam.