Part 1: On what befell Imam Husayn (a.s.) before Yazid bin Mu’awiyah claimed allegiance from him, until his Martyrdom
After the death of Imam Hasan (a.s.), a movement came about among the Shi’ah of Iraq. They wrote a letter to Imam Husayn (a.s.) stating their intention of deposing Mu’awiyah and their readiness (to support him) and swearing the allegiance (bay’ah) at his hands. In reply to their letter Imam Husayn (a.s.) wrote that he disagreed to it because a pact had been made between them and Mu’awiyah, which would not be violated by them until the period expired (till Mu’awiyah died), and when Mu’awiyah dies it would then be decided as to what would be done.
Mu’awiyah died in the middle of the month of Rajab 60 A.H. Yazid wrote a letter to Waleed bin Utba bin Abu Sufyan, who was appointed the governor of Madina by Mu’awiyah, to demand the oath of allegiance from Husayn ibn Ali (a.s.) immediately.