Observant Shiites and Sunnis fast from dawn to dusk during the holy month of Ramadan, which culminates with Eid ul-Fitr, which marks the first revelation of the Koran to Muhammad. Another major holiday is Eid al-Adha, which celebrates Ibrahim’s (Abraham’s) willingness to sacrifice his son on God’s command, though in the Muslim narrative the son in question is Ishmael, rather than Isaac.
But the Shiites also have two major holidays of their own Arbaeen and Ashura. Arbaeen is the 40th and final day of a mourning period for Muhammad’s grandson Hussein, who was slaughtered along with his outmatched followers in the desert near Karbala in 680 AD. The holiday is marked by millions of pilgrims making their way on foot to Karbala in Iraq. Most come from Iraq, but large numbers come from as far as Iran, India, and Pakistan. Ashura likewise commemorates Hussein and opens the 40-day mourning period.