The Day of Ashura is observed on the 10th day of the Islamic month of Muharram and recurs every year. It is commemorated worldwide by both Sunni and Shia Muslims, though they associate it with different historical events. Shia Muslims mourn the martyrdom of Husayn ibn Ali, the grandson of the Islamic prophet Muhammad, at the Battle of Karbala, marking this day with sorrowful observances. In contrast, Sunni Muslims recognize Ashura as the day when Moses fasted in gratitude for the liberation of the Israelites, following the tradition that the Prophet Muhammad adopted when he learned of the Jewish practice. Ashura is a public holiday in several Muslim-majority countries and regions with significant Shia populations, and Sunni Muslims often fast on this day, although it is not obligatory.