Tasu'a

'''Tasu'a''' () is the ninth day of Muharram, the first month of the Islamic calendar. Tasu'a is followed by Ashura, tenth of Muharram, which marks the death of Husayn ibn Ali, a grandson of the Islamic prophet Muhammad and the third Shia imam. Husayn refused on moral grounds to pledge his allegiance to the Umayyad caliph Yazid I () and was subsequently killed, alongside most of his male relatives and his small retinue, by the Umayyad army in the Battle of Karbala on Ashura 61 AH (680 CE). Among the Shia minority, mourning for Husayn is viewed as an act of protest against oppression, a struggle for God, and a means of securing the intercession of Husayn in the afterlife. Ashura is observed through mourning gatherings, processions, and dramatic reenactments. In such ceremonies, Shia mourners strike their chests to share in the pain of Husayn. Extreme self-flagellation, often involving self-inflicted bloodshed, remains controversial among the Shia, condemned by many Shia clerics, and outlawed in some Shia communities.

The battle in Karbala was to take place on Tasu'a but was delayed for a day. Husayn used this window to urge his followers to leave him and save their lives, which nearly all of them refused. The Umayyad army also offered safe passage to some close relatives of Husayn, notably his half-brother Abbas ibn Ali, which they also refused. By most accounts, Husayn and his men spent their last nightthe night of Tasu'ain prayer.