Yom Ashura or Ashura is the tenth day of Muharram, the first month in the Islamic calendar. It marks the day that Husayn ibn Ali, the grandson of the Islamic prophet Muhammad, was martyred in the Battle of Karbala. Ashura is a major holiday and occasion for pilgrimage in Shia Islam, as well as a recommended but non-obligatory day of fasting in Sunni Islam. Ashura shares origins with Yom Kippur from Judaism.