According to Wikipedia, Eid al-Adha (Īdu l-’Aḍḥā) "Festival of Sacrifice" or "Greater Eid" is a holiday celebrated by Muslims worldwide to commemorate the willingness of Ibrahim to sacrifice his son as an act of obedience to their God. It is the latter of two Eid festivals celebrated by Muslims, whose basis comes from the Quran. Like Eid al-Fitr, Eid al-Adha begins with a short prayer followed by a sermon. It annually falls on the 10th day of the month of Dhul Hijja of the lunar Islamic calendar. The festivities last for three days or more depending on the country. Eid al-Adha occurs the day after the pilgrims conducting Hajj, the annual pilgrimage to Mecca in Saudi Arabia by Muslims worldwide, descend from Mount Arafat. It happens to be approximately 70 days after the end of the month of Ramadan.