Arbaeen - "fortieth" Chehellom is a Shiite religious observance that takes place forty days after the Day of Ashura. It is dedicated to the martyrdom of Al-Hussein ibn Ali, the grandson of Muhammad, who was martyred on the 10th day of the month of Muharram. Imam Hussain ibn Ali and 71 of his companions were martyred by Ubaidallah ibn Ziyad's army under Yazid I at the Battle of Karbala in 61 AH (680 CE).
Arbaeen or forty days is also a common length of mourning following the death of a family member or loved one in many Muslim traditions. Arbaeen is the largest annual pilgrimage in the world, during which millions of people travel to the city of Karbala in Iraq.
According to tradition, the Arbaeen pilgrimage has been observed since AH 61 in the Islamic calendar (October 10, 680) after the Battle of Karbala or the following year. According to tradition, the first such meeting took place when Jabir ibn Abdallah, a Sahab and the first Arbayin pilgrim, made a pilgrimage to the burial place of Husayn. He was accompanied by Atiyyah ibn Saad because of his infirmity and probable blindness. According to tradition, his visit coincided with that of the surviving women of Muhammad's family, as well as Husayn's son and heir, Imam Ali ibn Husayn Zayn al-Abidin (also spelled Zein-ul-Abidin), who were all taken prisoner in Damascus. Yazid I, Umayyad caliph. Zayn al-Abidin survived the Battle of Karbala and led a secluded life of deep worship. He lived under pressure and harsh supervision from the Umayyad Caliphate.
According to legend, for twenty years, whenever water was placed in front of him, he wept. One day a servant said to him: "O son of the Messenger of Allah! Isn't it time for your sadness to end?" He replied: "Woe to you! Prophet Jacob had twelve sons, and Allah made one of them disappear. His eyes were white with constant weeping, his head turned gray with sorrow, and his back was bent in darkness, although his son was alive in this world. But I saw how my father, my brother, my uncle and seventeen members of my family were killed around me. How should my sorrow end? Arbain's speech was banned in some periods, the last of which was when Saddam Hussein (a Sunni who ruled as an Arab nationalist opposed to the Islamic resurgence) was president of Iraq.
For nearly 30 years, under Saddam's regime in Iraq, it was forbidden to publicly celebrate Arbaeen. Following the 2003 invasion of Iraq, the April 2003 celebration was broadcast worldwide.
Iran National and Public Holidays