Arbaeen, or Fortieth, is a Shi’a religious observation that occurs 40 days after the Day of Ashura, the commemoration of the martyrdom by beheading of Husayn bin Ali (a.s.), the grandson of the Prophet Muhammad (s.a.) which falls on the 20th day of the month of Safar.
Imam Husayn (a.s.) and his companions were martyred in the Battle of Karbala in the year 61 AH (680 CE). Forty days is the usual length of the time of mourning in many Islamic cultures.
The occasion reminds the faithful of the core message behind Husayn’s (a.s.) martyrdom: establishing justice and fighting injustice, no matter what its incarnation—a message that strongly influenced subsequent Shia uprisings against the tyranny of Umayyad and Abbasid rule.
In the first Arbaeen gathering in the year 62 AH, Jabir ibn Abdullah, a companion of the Prophet (s.a.), was one of the people who performed a pilgrimage to the burial site of Husayn (a.s.). Due to his infirmity and probable blindness, he was accompanied by Atiyya bin Saad. His visit coincided with that of the surviving female members of the Prophet’s (s.a) family and Husayn’s (a.s) son and heir Imam Sajjad (a.s.), who had all been held captive in Damascus by Yazid, the Umayyad Caliph.
Imam Sajjad (a.s.) had been too ill to participate in the Battle of Karbala. He later devoted his life to mourning and spreading the message of Imam Husayn’s (a.s) supreme sacrifice.