Arba'in
In Shia Islam, Arba'in (Arabic: الأربعين, lit. 'fortieth'), also spelled Arba'een, marks forty days after Ashura, which is the martyrdom anniversary of Husayn ibn Ali, grandson of the Islamic prophet Muhammad and the third Shia imam. Husayn was killed, alongside most of his relatives and his small retinue, in the Battle of Karbala on 10 Muharram 61 AH (680 CE) against the army of the Umayyad caliph Yazid ibn Mu'awiya (r. 680–683).