Editing Shia Islam (section)

=== Hasan, Husayn, and Karbala ===
{{main|Hasan ibn Ali|Husayn ibn Ali|Battle of Karbala}}
[[File:Bagh Toti 8167.jpg|left|thumb|[[Shah Abdol-Azim Shrine|S̲h̲āh ʿAbd al-ʿAẓīm Shrine]] in [[Ray, Iran|Rey]], [[Iran]], contains the tomb of [[Abd al-Azim al-Hasani|ʿAbd al-ʿAẓīm al-Ḥasanī]], a descendant of [[Hasan ibn Ali|Ḥasan ibn ‘Alī]] and a companion of [[Muhammad al-Taqi|Muhammad al-Taqī]].]]

Upon the death of ʿAlī, his elder son [[Hasan ibn Ali|Ḥasan]] became leader of the Muslims of Kufa. After a series of skirmishes between the Kufa Muslims and the army of Muawiyah, Ḥasan ibn Ali agreed to cede the caliphate to Muawiyah and maintain peace among Muslims [[Hasan–Mu'awiya treaty|upon certain conditions]]: The [[Umayyad tradition of cursing Ali|enforced public cursing of ʿAlī]], e.g. during prayers, should be abandoned; Muawiyah should not use tax money for his own private needs; There should be peace, and followers of Ḥasan should be given security and their rights; Muawiyah will never adopt the title of ''[[Amir al-Mu'minin]]'' ("commander of the believers"); Muawiyah will not nominate any successor.<ref>{{cite web |title="Solhe Emam Hassan"-Imam Hassan Sets Peace |url=http://www.valiasr-aj.com/fa/page.php?bank=question&id=1297 |url-status=live |archive-url=https://web.archive.org/web/20130311022151/http://www.valiasr-aj.com/fa/page.php?bank=question&id=1297 |archive-date=11 March 2013}}</ref><ref>{{cite book |title=تهذیب التهذیب |page=271}}</ref> Ḥasan then retired to [[Medina]], where in 670 CE he was poisoned by his wife [[Ja'da bint al-Ash'ath]], after being secretly contacted by Muawiyah who wished to pass the caliphate to his own son [[Yazid ibn Mu'awiyah|Yazid]] and saw Ḥasan as an obstacle.<ref>{{Cite book|last=Madelung|first=Wilfred|title="Ḥasan b. ʿAli b. Abi Ṭāleb". [[Encyclopædia Iranica]]. Retrieved 7 November 2018|year=2003}}</ref>[[File:Brooklyn Museum - Battle of Karbala - Abbas Al-Musavi - overall.jpg|thumb|right|250px|''Battle of Karbala'', painting by the [[Isfahan]]-based Persian artist Abbas Al-Mousavi, [[Brooklyn Museum]] (between 1868 and 1933)]]

[[Husayn ibn Ali|Ḥusayn ibn ʿAlī]], ʿAlī's younger son and brother to Ḥasan, initially resisted calls to lead the Muslims against Muawiyah and reclaim the caliphate. In 680 CE, Muawiyah died and passed the caliphate to his son [[Yazid I|Yazid]], and breaking the treaty with Ḥasan ibn ʿAlī. Yazid asked Husayn to swear allegiance (''[[bay'ah]]'') to him. ʿAlī's faction, having expected the caliphate to return to ʿAlī's line upon Muawiyah's death, saw this as a betrayal of the peace treaty and so Ḥusayn rejected this request for allegiance. There was a groundswell of support in Kufa for Ḥusayn to return there and take his position as caliph and Imam, so Ḥusayn collected his family and followers in Medina and set off for Kufa.<ref name=":2" />

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| image1            = حرم_الامام_الحسين.jpg
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| image2            = Arba'een Pilgrims in Bayn al-Harmian 019.jpg
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| footer            = Left: the [[Imam Husayn Shrine|Shrine of Imam Ḥusayn]]; right: the shrine premises during [[Arba'een]]
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En route to Kufa, Husayn was blocked by an army of Yazid's men, which included people from Kufa, near [[Karbala]]; rather than surrendering, Husayn and his followers chose to fight. In the [[Battle of Karbala]], Ḥusayn and approximately 72 of his family members and followers were killed, and Husayn's head was delivered to Yazid in Damascus. The Shi'a community regard Ḥusayn ibn ʿAlī as a martyr (''[[shahid]]''), and count him as an Imam from the {{transliteration|ar|Ahl al-Bayt}}. The Battle of Karbala and martyrdom of Ḥusayn ibn ʿAlī is often cited as the [[Shia–Sunni relations|definitive separation between the Shia and Sunnī sects of Islam]]. Ḥusayn is the last Imam following ʿAlī mutually recognized by all branches of Shia Islam.<ref>Discovering Islam: making sense of Muslim history and society (2002) Akbar S. Ahmed</ref> The martyrdom of Husayn and his followers is commemorated on the [[Ashura|Day of Ashura]], occurring on the tenth day of Muharram, the first month of the Islamic calendar.<ref name=":2" />