Al-Husayn ibn Ali ibn Abi Talib (Arabic: lHsyn bn `ly bn 'by Tlb; 10 October 625 - 10 October 680) (3 Sha'aban AH 4 (in the ancient (intercalated) Arabic calendar) - 10 Muharram AH 61) (his name is also transliterated as Husayn ibn 'Ali, Husain, Hussain and Hussein), was a grandson of the Islamic Nabi (Arabic: nabiy, Prophet) Muhammad, and son of Ali ibn Abi Talib (the first Shia Imam and the fourth Rashid caliph of Sunni Islam), and Muhammad's daughter, Fatimah. He is an important figure in Islam as he was a member of the Bayt (Arabic: bayt, Household) of Muhammad, and Ahl al-Kisa' (Arabic: 'ahl lkisa, People of the Cloak), as well as being the third Shia Imam.

According to the Shi'ah, Husayn was the third Imam for a period of ten years after the death of his brother Hasan in CE 669, all of this time but the last six months coinciding with the caliphate of Mu'awiyah. After the peace treaty with Hasan, Mu'awiyah set out with his troops to Kufa, where at a public surrender ceremony Hasan rose and reminded the people that he and Husayn were the only grandsons of Muhammad, and that he had surrendered the reign to Mu'awiyah in the best interest of the community: "O people, surely it was God who led you by the first of us and Who has spared you bloodshed by the last of us. I have made peace with Mu'awiyah, and I know not whether haply this be not for your trial, and that ye may enjoy yourselves for a time." declared Hasan.  In the nine-year period between Hasan's abdication in 41/660 and his death in 49/669, Hasan and Husayn retired in Medina trying to keep aloof from political involvement for or against Muawiyah.  Shi'ite feelings, however, though not visible above the surface, occasionally emerged in the form of small groups, mostly from Kufa, visiting Hasan and Husayn asking them to be their leaders - a request to which they declined to respond. Even ten years later, after the death of Hasan, when Iraqis turned to his younger brother, Husayn, concerning an uprising, Husayn instructed them to wait as long as Muawiyah was alive due to Hasan's peace treaty with him. Later on, however, and before his death, Muawiyah named his son Yazid as his successor.

What did he say to start this
According to the Shi'ah, Husayn was the third Imam for a period of ten years after the death of his brother Hasan in CE 669,