Pronounced “EED-uhl-ad-ha.” Known as the Feast of Sacrifice, it concludes the annual observance of the pilgrimage to Mecca known as hajj. Muslims everywhere observe Eid al-Adha with community prayers and a feast, whether or not they are on hajj. Eid al-Adha shifts dates every year because Muslims use a lunar calendar that only includes about 354 days. Eid al-Adha commences with the sighting of the new moon. See hajj.