Alī ibn Abī Ṭālib

Ali ibn Abi Talib (; ) was the fourth Rashidun caliph who ruled from until his assassination in 661, as well as the first Shia Imam. He was the cousin and son-in-law of the Islamic prophet Muhammad. Born to Abu Talib ibn Abd al-Muttalib and Fatima bint Asad, Ali was raised in the household of his cousin Muhammad and was among the first to accept his teachings.

Ali played a pivotal role in the early years of Islam when Muslims were severely persecuted in Mecca. After the immigration () to Medina in 622, Muhammad gave his daughter Fatima to Ali in marriage and swore a pact of brotherhood with him. Ali served as Muhammad's secretary and deputy in this period, and was the flag-bearer of his army. Numerous sayings of Muhammad praise Ali, the most controversial of which was uttered in 632 at the Ghadir Khumm, "Whoever I am his , then Ali is his ." The interpretation of the polysemous Arabic word is disputed: for Shia Muslims, Muhammad thus invested Ali with his religious and political authority, while Sunni Muslims view this as a mere statement of friendship and rapport. When Muhammad died in the same year, a group of Muslims met in the absence of Ali and appointed Abu Bakr () as their leader. Ali later relinquished his claims to leadership and resigned from public life during the reigns of Abu Bakr and his successor, Umar (). Even though his advice was occasionally sought, the conflicts between Ali and the first two caliphs are epitomized by his refusal to follow their practices. This refusal cost Ali the caliphate to the benefit of Uthman (), who was thus appointed to succeed Umar by the electoral council. Ali was also highly critical of Uthman, who was widely accused of nepotism and corruption. Yet Ali also repeatedly mediated between the caliph and the provincial dissidents angered by his policies.