Who killed Uthman (may Allah be pleased with him)? What were their motives? What did Imam Ali (may Allah be pleased with him) do to those who participated in his killing? Did Mu'awiyah (may Allah be pleased with him) take action after assuming the Caliphate? Was anyone of them prosecuted during any era?

Caliph Uthman ibn Affan, may Allah be pleased with him, was killed on the 18th of Dhul-Hijjah in the year 35 AH by a rebellious group numbering two thousand, who had agreed to kill him. Kinana ibn Bishr al-Tujaybi directly participated in his killing. It is also said that Sudan ibn Humran al-Sakuni did so after being stabbed by Qutayra al-Sakuni, and Ghafiqi ibn Harb al-Akki initiated striking him. A group from the people of Basra and Kufa also participated with them.

Allah Almighty pursued those who killed Uthman, may Allah be pleased with him, and most of them died killed. Some were killed immediately, some after many long years, and some died poisoned.

As for Ali, may Allah be pleased with him, he was unable to prosecute them due to the instability of the situation after his pledge of allegiance, their mixing with his army, and the outbreak of seditions that led to the Battle of the Camel, and then the independence of some lands.

As for Muawiya, may Allah be pleased with him, he did not prosecute those who remained of them because most of them were killed before his caliphate, and because of the condition set by Al-Hasan ibn Ali upon him to spare the blood of all Muslims and cease fighting.

None of Uthman's killers were prosecuted by Ali, Hasan, or Muawiya, except for those killed by Al-Hajjaj.

As for the reasons for their killing of Uthman, may Allah be pleased with him, they stem from matters they held against him, including his appointment of his relatives and spending on them, his punishment of some companions, and his unifying the people upon one Mushaf, in addition to personal motives, greed, and resentment towards the religion from some of them.