Arba'een (Martyrdom of Husayn ibn Ali) Date in the current year: August 26, 2024

Husayn ibn Ali was the son of Muhammad's daughter Fatima Zahra and the first Imam of Shia Islam Ali ibn Abi Talib. He became the third Shia Imam in 669, following the death of his brother Hasan ibn Ali. Husayn remained Imam until 680, when he and his 72 companions were killed in the Battle of Karbala by the army of Yazid I.

Shia Muslims commemorate the Battle of Karabala on the 10th day of Muharram, known as the Day of Ashura. This day is the beginning of a traditional forty-day period of mourning. Arba'een is the culmination of the mourning period that commemorates the martyrdom of Imam Husayn. In Iran, where Shia Islam is an official religion, it is a public holiday.

Arba'een is marked with a large pilgrimage. Millions of Muslims go to the city of Karbala in Iraq, where Husayn ibn Ali died and was buried. The pilgrims visit the Imam Husayn Shrine, which comprises his burial site and the mosque. Although Arba'een is a Shia observance, many Sunni Muslims partake in the pilgrimage as well.