Eid-e-Shuja, also known as Eid-e-Zahra, is a ritual festival observed by most Twelver Shia Muslims. It is celebrated on the 9th day of the month of Rabi al-Awwal of the Islamic year. The festival marks the end of the two-month mourning period after the events of the Karbala massacre for Shia Muslims. It is also known as the "Eid of the brave and courageous companions of Imam Hussein ibn Ali" who fought in the battle of Karbala. The festival is a carnival-type of celebration in which social roles are reversed and communal norms upturned. It generally functions as a more lighthearted counterpart of the Tazieh passion plays during the mourning of Muharram, which commemorate the death of the prophet Muhammads grandson Husayn ibn Ali at the Battle of Karbala in 680. The festival is also a veneration of the day when the murderers of Fatimahs son were caught and is considered an occasion of great exultation and happiness.