The Battle of Siffin (Arabic: صفين‎; May–July 657 CE) occurred during the First Fitna, or first Muslim civil war, with the main engagement taking place from July 26 to July 28. It was fought between Ali ibn Abi Talib and Muawiyah I, on the banks of the Euphrates river, in what is now Ar-Raqqah, Syria. Following the controversial murder of Uthman ibn Affan, Ali had become Caliph but struggled to be accepted as such throughout the Muslim Empire. Muawiyah, the governor of Syria, was a kinsman of the murdered Caliph, and wanted the murderers brought to justice. He considered that Ali was unwilling to do this, and so Muawiyah rebelled against Ali, who attempted to put down the rebellion. The result was the engagement at Siffin. However, the battle was indecisive, and the two parties agreed to an arbitration, which was equally indecisive. The battle and arbitration served to weaken Ali's position, but did not resolve the tensions that were plaguing the empire. To the Shia, Ali ibn Abi Talib was the first Imam. To Sunnis, Ali ibn Abi Talib was the fourth Rashidun Caliph, and Muawiyah the first Caliph of the Ummayyad dynasty. The events surrounding the battle are highly controversial between Sunni and Shia, and serve as part of the split between the two groups.

ʻAmmār ibn Yāsir b. ʿĀmir b. Mālik Abū l-Yaqẓān (Arabic: عمار بن یاسر‎) was one of the companions of the Islamic prophet Muhammad. He was one of the Muhajirun, and referred to as by Shia Muslims as one of the Four Companions.

Ammār was born in the Year of the Elephant, which was the same year as Muhammad. ʻAmmār was a friend of Muhammad even before conversion and was one of the intermediaries in Muhammad's marriage to Khadijah bint Khuwaylid. His mother was Sumayyah bint Khayyat and his father was Yasir ibn Amir. Yasir and Sumayyah were pagan converts to Islam who were tortured and crucified in the last year before the Hijra . ʻAmmār and his family were repeatedly tortured by Meccan polytheists . Once when ʻAmmār was being tortured, it is reported that he spoke idolatrously and contradicted his faith. This incident is often used as an example of taqiyya (“the concealment of one’s true beliefs in times of adversity” ) because ʻAmmār only denounced his beliefs because he was being tortured so horribly. After the persecution of Muslims was over, Hamza and the Muhammad's other companions went to the location where the torture and persecution took place; they found every persecuted Muslim dead except ʻAmmār, who had survived the torture. ʻAmmār’s parents were both among the group of persecuted Muslims who did not survive. Abu Jahl killed his mother Sumayyah, who is considered the first Muslim martyr.