Event of the mubahala in the context of Ahl al-Kisa

Hasan ibn Ali (Arabic: الحسن ابن علي, romanized: al-Ḥasan ibn ʿAlī; c. 625 – 2 April 670) was an Alid political and religious leader. The eldest son of Ali and Fatima and a grandson of the Islamic prophet Muhammad, Hasan briefly ruled as caliph from January 661 until August 661. He is considered as the second Imam in Shia Islam, succeeding Ali and preceding his brother Husayn. As a grandson of the prophet, he is part of the ahl al-bayt and the ahl al-kisa, and also participated in the event of the mubahala.

During the caliphate of Ali (r. 656–661), Hasan accompanied him in the military campaigns of the First Fitna. Following Ali's assassination in January 661, Hasan was acknowledged caliph in Kufa. His sovereignty was not recognized by Mu'awiya ibn Abi Sufyan (r. 661–680), the governor of Syria, who led an army into Kufa while pressing Hasan for abdication in letters. In response, Hasan sent a vanguard under Ubayd Allah ibn al-Abbas to block Mu'awiya's advance until he arrived with the main army. Meanwhile, Hasan was severely wounded in an abortive assassination attempt by the Kharijites, a faction opposed to both Ali and Mu'awiya. This attack demoralised Hasan's army and led to widespread desertion. Ubayd Allah and most of his troops also defected after Mu'awiya bribed him. In August 661, Hasan signed a peace treaty with Mu'awiya on the condition that the latter should rule in compliance with the Quran and the Sunnah, a council should appoint his successor, and Hasan's supporters would receive amnesty. Hasan retired from politics and abdicated in Medina where he died either from illness or poisoning, though the early sources are nearly unanimous that he was poisoned. Mu'awiya is commonly viewed as the instigator in the murder of Hasan, which removed an obstacle to the succession of his son Yazid I (r. 680–683).

Husayn ibn Ali (Arabic: الحسين بن علي, romanized: al-Ḥusayn ibn ʿAlī; 11 January 626 – 10 October 680 CE) was a social, political and religious leader in early medieval Arabia. The grandson of the Islamic prophet Muhammad and an Alid (the son of Ali ibn Abi Talib and Muhammad's daughter Fatima), as well as a younger brother of Hasan ibn Ali, Husayn is regarded as the third Imam in Shia Islam after his brother, Hasan, and before his son, Ali al-Sajjad. Husayn is a prominent member of the Ahl al-Bayt and is also considered to be a member of the Ahl al-Kisa and a participant in the event of the mubahala. Muhammad described him and his brother, Hasan, as the leaders of the youth of paradise.

During the caliphate of Ali, Husayn accompanied him in wars. After the assassination of Ali, he obeyed his brother in recognizing the Hasan–Mu'awiya I treaty, despite it being suggested to do otherwise. In the nine-year period between Hasan's abdication in AH 41 (660) and his death in AH 49 or 50 (669 or 670), Hasan and Husayn retreated to Medina, trying to keep aloof from political involvement for or against Mu'awiya I. After the death of Hasan, when Iraqis turned to Husayn, concerning an uprising, Husayn instructed them to wait as long as Mu'awiya was alive due to Hasan's peace treaty with him.

Ahl al-Kisa (Arabic: أَهْل ٱلْكِسَاء, romanized: ʾAhl al-Kisāʾ, lit. 'people of the cloak' ), also known as the Al al-Aba (Arabic: آل ٱلْعَبَاء, romanized: ʾĀl al-ʿabāʾ, lit. 'family of the cloak' ), are Muhammad the Islamic prophet, his daughter Fatima, his cousin and son-in-law Ali, and his two grandsons Hasan and Husayn.

The name has its origins in the hadith of the cloak (Arabic: ٱلْكِسَاء, romanized: al-kisāʾ) and the event of the mubahala, both widely reported by Sunni and Shi'i authorities as evidence of the high spiritual rank of the "people of the cloak" in Islam. In Shi'a Islam, Ali, Hasan, and Husayn are the first three Imams and the rightful political and spiritual successors of Muhammad. Shi'a who are not Zaydis also regard the Ahl al-Kisa as infallible and believe in the redemptive power of their pain and martyrdom.