Great Mosque of Kufa in the context of Hani ibn Urwa

Ali ibn Abi Talib, the fourth Rashidun caliph (r. 656–661) and the first Shia Imam, was assassinated during the morning prayer on 28 January 661 CE, equivalent to 19 Ramadan 40 AH. He died of his wounds about two days after the Kharijite dissident Ibn Muljim struck him over his head with a poison-coated sword at the Great Mosque of Kufa, located in Kufa, in present-day Iraq. He was about sixty-two years of age at the time of his death.

Ibn Muljim had entered Kufa with the intention of killing Ali, probably in revenge for the Kharijites' defeat in the Battle of Nahrawan in 658. He found two accomplices in Kufa, namely, Shabib ibn Bujra and Wardan ibn al-Mujalid. Unlike Ibn Muljim, the swords of these two missed Ali and they fled, but were later caught and killed. Before his death, Ali requested either a meticulous application of lex talionis to Ibn Muljim or his pardon, and he was later executed by Hasan, the eldest son of Ali. By most accounts, also involved in the assassination was al-Ash'ath ibn Qays, the influential Kufan tribal leader whose loyalty to Ali is often questioned in the early sources. The assassination of Ali paved the way for his rival Mu'awiya to found the Umayyad Caliphate. The shrine of Ali in Najaf, near Kufa, is a major destination for Shia pilgrims.

Abu al-ʿAbbās Abd Allāh ibn Muḥammad ibn ʿAlī ibn ʿAbd Allāh ibn al-ʿAbbās (Arabic: أبو العباس عبد الله ابن محمد ابن علي‎; 721/722 – 8 June 754), known by his laqab al-Saffah (Arabic: السفّاح), was the first caliph of the Abbasid Caliphate, one of the longest and most important caliphates in Islamic history.

His laqab al-Saffāḥ means "the Blood-Shedder". It may refer to his ruthless tactics, or perhaps it was used to intimidate his enemies. It was during his inaugural homage as Caliph, delivered in the Great Mosque of Kufa, that he called himself "al-Saffah" ("the Blood-Shedder"), and this title has deservedly stuck to him due to his hunting down and massacre of the Umayyads in cold blood.