Hasan–Mu'awiya treaty

The Hasan–Mu'awiya treaty was a political peace treaty signed in 661 between Caliph Hasan ibn Ali and Mu'awiya I (r. 661–680) to bring the First Fitna (656–661) to a close. Under this treaty, Hasan ceded the caliphate to Mu'awiya on the condition that the latter should rule in compliance with the Quran and the sunna, a council should appoint his successor, and Hasan's supporters would receive amnesty. Upon accession, Mu'awiya publicly recanted his earlier promises, while Hasan retired from politics in Medina, and was later killed in 670 by poisoning. Mu'awiya is commonly viewed as the instigator in the murder of Hasan, which removed an obstacle to the succession of his son Yazid (r. 680–683), whose nomination violated the treaty with Hasan. Throughout his reign, Mu'awiya also prosecuted notable partisans of Hasan and his father Ali.