he fled to Mecca in disgrace, whereas Amr was well-received by Mu'awiya upon his return to Syria. The common view is that the arbitration failed, or was inconclusive. This sentiment is perhaps summed up by the early historian Khalifah ibn Khayyat () in one sentence, "The arbiters agreed on nothing." The arbitration nevertheless strengthened the Syrians' support for Mu'awiya and weakened the position of Ali. It also gave the former an opportunity to regroup, according to Momen. Aftermath After the conclusion of the arbitration, Syrians pledged their allegiance to Mu'awiya as the next caliph in 659, or by the end of April-May 658, according to Bahramian. Upon learning that Mu'awiya had declared himself caliph, Ali broke off all communications with him and introduced a curse on him in his congregational prayers, following the precedent of Muhammad. Mu'awiya soon reciprocated by introducing a curse on Ali, his sons, and his top general. With the news of their violence against civilians, Ali had to postpone his new Syria campaign to subdue the Kharijites in the Battle of Nahrawan in 658. Just before embarking on his second campaign to Syria in 661, Ali was assassinated by a Kharijite during the morning prayers at the Mosque of Kufa. In the long term, it is the opinion of Ayoub that the Battle of Siffin crystalized the emerging divide in the Muslim community and changed its course. References Sources Further reading Battles involving the Rashidun Caliphate Battles involving the Umayyad Caliphate First Fitna Shia days of remembrance 650s conflicts 657