In many cultures, killing an animal is traditionally reserved for special occasions, often regarded with sacred significance. Sacrifice involves conscious participation in cosmic movement from life to death to the renewal of life. In the Islamic world such an occasion arises on the Feast of the Sacrifice. On the tenth day of Dhu'l Hijjah, the month of the Pilgrimage, Muslims on pilgrimage and at home re-enact the experience of Abraham and Ishmael, recounted in the thirty-seventh chapter of the Qur'an. Abraham received a dream in which he was asked by God to sacrifice that which was dearest to him. Interpreting the dream literally, he chose his son Ishmael, who accompanied him willingly to the sacrificial altar. With this act both father and son submitted their will and devotion completely to the will of God as they understood it. God then substituted a ram in place of Ishmael, thereby acknowledging the faith of father and son, affirming the validity of sacrifice, and implicitly condemning human sacrifice. The sacrifice of the ram symbolizes the sacrifice of the self at the altar of God.
When will the feast of the appearance of Your face arrive,
so that lovers may offer up their hearts and souls
as a sacrifice in fidelity to you?
The sacrifice performed on 'Id al-Adha usually involves an animal acceptable as food, without blemish or defect. It is obtained in advance of the feast, fed for several days by the owner, and treated with compassion, ideally resulting in the development of a bond between human and animal. The act of sacrifice is accompanied by the words, "Bismillah, Allahu akbar" (In the name of God, God is most great). The meat should then be divided one third for the poor, one third for relatives and friends, and one third for the family itself.
from Serving the Guest: A Sufi Cookbook