Today marks the second religious festival of the Islamic calendar, after the Festival of the Breaking of the Fast, عيد الفِطر (ʿīd al-fiṭr, Eid al-Fitr), that follows Ramadan. It is called the Festival of the Sacrifice, عيد الأضحى (ʿīd al-aḍḥá, Eid al-Adha), and is the more important of the two, informally known as the “Greater Eid” (عيد الكَبير, ʿīd al-kabīr).
The festival commemorates an event that should be familiar to anybody who has some knowledge of the Bible, the episode in Genesis known as the “Binding of Isaac” (Genesis 22). God commands Abraham to sacrifice his son and Abraham, understandably conflicted, ultimately chooses to obey God even at the cost of his son, only to have an angel stop him just as he’s about to kill the boy, Abraham having proved his devotion to God by his willingness to obey even such a difficult command. This story was retold in the Qurʾān (37:100-109) and is part of the Islamic narrative about Abraham (إبراهيم, Ibrāhīm). Mainstream Islam says that it was Ishmael (إسماعيل, Ismāʿīl) who was supposed to be sacrificed by Abraham, rather than Isaac (إسحاق, Isḥāq), though early Muslim scholars disputed this point because the identity of the son is not specified in the Qurʾān’s version of the story.
Eid al-Adha is intimately connected with the annual Hajj pilgrimage to Mecca, which is itself very closely connected to the Islamic narrative of the life of Abraham/Ibrahim. If you’re familiar with the rituals of the Hajj then you know that the pilgrims celebrate Eid al-Adha after descending from Mount Arafat and returning to Mina, where they stone three pillars or walls meant to symbolize the three times that Satan attempted to sway Ibrahim from obeying God’s command, then segue into the traditional festival celebration. Muslims around the world, not only on Hajj, celebrate this festival at the same time. Our discussion of the customs and rituals involved with this Eid will focus on what believers who are not on Hajj do to commemorate the holiday. The celebration has its roots in the Qurʾān (2:196), which commands that all believers who are not on Hajj nevertheless commemorate this festival with animal sacrifice.
The celebration begins with a special Eid prayer, to be performed after the sun is fully risen but before the noon prayer. This must be performed in a communal mosque if at all possible. Friends and family members will visit one another and offer Eid greetings. The same greetings that are used for Eid al-Fitr also apply here: عيد مُبارَك (ʿīd mubārak, Eid Mubarak), “Blessed Festival (Eid)” and عيد سَعيد (ʿīd saʿīd, Eid Saeed), “Happy Festival.” Gifts are often given to children, something simple like candy or a little cash. But the most important ritual, for those with the means to do so, is the sacrifice of the best herd animals, often cattle, but also other حَلال (ḥalāl, “lawful”) animals like sheep, goats, camels, etc. (not pigs, obviously); these “sacrificial” animals are called أضحية (aḍḥīyah). Tens of millions of animals are slaughtered worldwide over the holiday, and their meat is divided into three parts: one for the family to keep, a second to give to friends and relatives, and a third to be given to the poor. No Muslim is allowed to go hungry during the festival, and it is incumbent upon all Muslims of means to provide for the poor. The holiday lasts at least 4 days, but local custom may extend it beyond this (I think the UAE takes at least a week, for example, but I don’t know how many days other places celebrate).