In 661 CE, after Ali's assassination, Hasan ibn Ali attained to the caliphate. There was a military conflict between Caliph Ali and Muawiya ibn Abu Sufyan ; and to avoid the agonies of a further civil war, Hasan signed the Hasan–Muawiya treaty with Muawiyah. According to the treaty, Hasan ceded the caliphate to Muawiyah but the latter could name no successor during his reign; instead, he was to let the Islamic world choose its successor afterward.
Background
was the governor of the Levant region of Arabia at the time. He had refused Ali's repeated demands for allegiance, when Ali was elected as the fourth Caliph, and was therefore in conflict with him. However, when Ali was assassinated and people gave allegiance to Hasan, Muawiyah prepared to attack Hasan. As a result there were repeated skirmishes between the armies of Hasan and Muawiyah with no conclusive outcome. Muawiyah who had already started negotiations with Hasan, sent high-level envoys, while committing himself in a witnessed letter to appoint Hasan his successor and give him whatever he wished. Hasan accepted the offer in principle and sent Amr ibn Salima al-Hamdani al-Arhabl and his own brother-in-law Muhammad ibn al-Ash'ath back to Muawiyah as his negotiators, together with the envoys of the latter. Muawiyah then wrote a letter saying that he was making peace with Hasan on the basis that Hasan would inherit the reign after him. He swore that he would not seek to harm him; and that he would give him 1,000,000 dirhams from the treasury annually, along with the land tax of Fasa and Darabjird; to which Hasan was to send his own tax agents to collect it. The letter was witnessed by the four envoys and dated in August 661. When al-Hasan read the letter he commented: "He is trying to appeal to my greed for a matter which, if I desired it, I would not surrender to him." Then he sent Abd Allah ibn al-Harith, whose mother Hind was Muawiyah's sister, to Muawiyah, instructing him: "Go to your uncle and tell him: If you grant safety to the people I shall pledge allegiance to you." After which, Mu'awiyah gave him a blank paper with his seal at the bottom, inviting Hasan to write on it whatever he desired.
The treaty
According to Jafri, historians like Ya'qubi and Al-Masudi do not mention the terms of peace treaty at all. Other historians such as Dinawari, Ibn Abd al-Barr and Ibn al-Athir records different accounts of the conditions. And the timing of the blank sheet sent by Muawiyah to Hasan was confusing in Tabari's account. The most comprehensive account, which explains the different ambiguous accounts of other sources, according to Jafri, is given by Ahmad ibn A'tham, which must have taken it from al-Mada'ini. Madelung's view is close to that of Jafri when he stipulates that Hasan surrendered the reign over the Muslims to Muawiya on the basis that "he act in accordance with the Book of God, the Sunnah of His Prophet and the conduct of the righteous caliphs. Muawiyah should not be entitled to appoint his successor but that there should be an electoral council ; the people would be safe, wherever they were, with respect to their person, their property and their offspring; Muawiyah would not seek any wrong against Hasan secretly or openly, and would not intimidate any of his companions." The letter was testified by Abd Allah ibn al-Harith, and Amr ibn Salima and transmitted by them to Muawiyah for him to take recognition of its contents and to confirm his acceptance. Hasan, thus, surrendered his control of Iraq in Rabi II 41/August 661 after a reign of seven months.
Narrations
Narrated by Al-Hasan Al-Basri: writes: The main condition Hasan ibn Ali imposed on Muawiya for handing over power was to be just to the people and keep them safe and secure. Following is the extract of the treaty between Imam Hassan and Muawiya:
Authority will be handed to Muawiya provided that he should act according to the Book of Allah, the Sunna of the Prophet, and the behavior of the righteous Caliphs
Authority should be for Imam Hassan after Muawiya, and if an accident occurs, authority should go to Imam Hussain, Muawiya has no right to entrust authority to anyone
Muawiya should abandon cursing the Commander of the faithful and the practice of using the qunut in the salat against him, Muawiya should also not mention Imam Ali unless in a good manner.
He should exclude what is in the treasury of Kufa, that is five million. So handing over authority does not include it. Muawiya should send al-Husayn one million dirhams a year, he should prefer the children of Hashim in giving and gifts to the banu Abd Shams, and should divide one million among the sons of those who were killed with the Commander of the faithful at the Battle of the Camel and the Battle of Siffin, and should spend that from the taxes of Dar Abjard.
The people should be safe wherever they are in the earth of Allah. Muawiya should give security to all races. The companions of Imam Ali should be given security wherever they are. Muawiya should not seek a calamity secretly or openly for Imam Hassan, nor for Imam Hussein, nor for any of the Prophet’s Ahlul Bayt.
After the peace treaty, Hasan received Mu'awiya's letter asking him to counter the khariji threat. He sent him the following reply:
