According to Muslim historians, the third caliph Uthman b. al-Affan was assassinated because of his financial mismanagement and religious digression. The prominent historian Ibn Sa’d says that Uthman b. al-Affan governed for twelve years. For the first six years, he was very popular, but in the second six years, he brought his family members and clan to political power and flooded them with money, whereby he angered the people because those whom he appointed as administrators and governors over all the Islamic lands were corrupt. Al-Tabari and Ibn al-Atheer go further and agree that financial mismanagement was not the only reason why Uthman was killed; nonetheless, they say that they do not want to mention the other reasons because they do not want to stir the tension in the public. Other sources are more vocal about what actually happened during that time.
Before assuming the caliphate, Uthman had agreed to follow the policies of his predecessors. However, after becoming the caliph, he reverted to the jahiliyyah practice of favoring his own relatives. Aware of Uthman’s tendencies in that direction, Umar had previously warned him to refrain from nepotism because the people would reject it and the Quraysh would lose power, however Uthman did not heed his advice.
Unlike Abu Bakr and Umar, Uthman filled the official positions with his own tribesmen, such as Abu Sufyan, Marwan b. al-Hakam, Mu’awiyah b. Abu Sufyan, al-Waleed b. Uqbah, Abdullah b. Abi Sarh, and Sa’ed b. al-Aas. In doing so, he angered many people, even those on the side of Quraysh, such as Lady Aishah.
Particularly upset were those who lost power due to Uthman’s nepotism, such as Amr b. al-Aas, who lost Egypt; al-Mugheerah b. Shu’bah, who lost Kufa; and Abu Musa al-Ashari, who lost Basra. Adding insult to injury, Uthman then appointed incompetent and corrupt individuals from among the Bani Umayyah to fill those positions. As a result, some of those townships revolted and in Kufa for example, the people ousted Uthman’s choice and reinstated Abu Musa al-Ashari.
The administrative mismanagement began with al-Hakam b. al-Aas and his son Marwan. The Holy Prophet had exiled both of them from Madinah because they had been agitating the populace. During the caliphates of Abu Bakr and Umar, both leaders refused permission for them to return. However, when Uthman came to power, not only did he bring back al-Hakam b. al-Aas and Marwan, but he gave al-Hakam b. al-Aas 100,000 dirhams, and he gave his own daughter, Umme Aban in marriage to Marwan. As his son-in-law, Marwan became a close minister to Uthman and in turn, Uthman presented him with many gifts, such as allocating him all of the income of Africa. He even gave Marwan’s brother Harith b. al-Hakam 300,000 dirhams.
Uthman favored his own relatives for government positions despite their incompetence, and in doing so, he alienated the rest of the Muslims, especially the Muhajireen and the Ansar. Rumor spread in the city of Kufa that Uthman wanted to honor his stepbrother at the expense of the ummah of Muhammad.
In truth, Uthman replaced Sa’d b. Abi al-Waqqas, the well-liked governor of Kufa, with his step-brother al-Waleed b. Uqbah and thereby earned the wrath of the people, who asked whether it was just to replace Sa’d b. Abi al-Waqqas, whom they felt was moderate, kind, and forgiving with his own step-brother, who was in their words, “stupid, irreligious, and corrupt (ahmaq, majin, wa fajir).”
He also allocated the entire income of Africa, from Tripoli to Tangiers, to another stepbrother, Ibn Abi Sarh and made him supreme governor of Egypt instead of governor of the countryside. In addition, he expanded the authority of Mu’awiyah b. Abu Sufyan, which had been limited to Damascus during the time of Umar, to include all of Shaam, which encompassed Syria, Jordan, Lebanon, Palestine, and other areas at that time. He treated others from the Bani Umayyah in a similar fashion.
These actions brought him into conflict with the people, not because they disliked the Bani Umayyah, but because those whom he appointed were dishonest and corrupt. However, when historians analyze the reasons behind Uthman’s assassination, they say that it was not only because he departed from the egalitarian spirit of the Qur’an and allowed his clansmen to take from the people at a time of economic crisis and poverty, but that bidah (religious innovation) was a factor as well. Closer investigation of that period reveals that Uthman did in fact attempt to make changes to the religion.
Uthman’s nepotism led to his assassination and the awaited succession of Ali b. Abi Talib to the caliphate. After Ali was murdered, power again shifted to the Quraysh group under the rule of Mu’awiyah b. Abu Sufyan. Learning from Uthman’s errors, Mu’awiyah balanced political with tribal alliances and followed Umar’s practice of appointing allies from outside his own tribe to official positions. Hence, Amr b. al-Aas, al-Mugheerah b. al-Shu’bah, Abu Huraira, al-Numan b. Basheer, and Abd al-Rahman b. Khalid all found places in the new caliphate under Mu’awiyah, and even Lady Aishah was pacified.
 Ibn Sa’d, Al-Tabaqat al-Kubra, 3:64
 Tarikh al-Tabari 4:365; Ibn al-Atheer, Al-Kamil fil-Tarikh, 3:167
 Ibn al-Atheer, Al-Kamil fil-Tarikh, 3:67
 Ibn Sa’d, al-Tabaqat, 5:33
 Ansab al-Ashraf, 5:32
 Ansab al-Ashraf, 5:30; Ibn Abil Hadid, Sharh Nahjul-Balaghah, 3:17