Islam
Eid-ul-Adhia is a festival that is celebrated on the 10th of Dhul Hijja and marks the close of the Hajj ceremony or Pilgrimage to the Ka'aba. 

A Muslim is required to perform the pilgrimage at least once in his lifetime, provided that he can afford the cost of the journey, is not indebted to anyone and is not otherwise prevented from performing the Haj. Those who unable to perform the pilgrimage join in the Eid-ul-Adhia ceremony at their own places. 

The Eid is celebrated with great solemnity and reverence everywhere. Like Eid-ul-Fitr, Muslims make preparations several days before the festival. The animals to be sacrificed are bought well before the Eid day by those who can afford to do so. These animal should be free from all physical defects and should be fully grown. In case of sheep, goat or lamb, one animal suffices for one household, while a cow or a camel can be shared by upto seven families. On the day of the Eid, Muslims assemble in the Eid-gah or in the large mosques of the town for Eid Prayer Service. The Eid Prayer is comprised of two Raka'as and offered in the same manner as Eid-ul-Fitr. Generally no breakfast is served on this Eid, and those who offer sacrifice do not eat anything until after they have sacrificed the animal. After the prayer the Imam delivers a sermon in which he explains the significance of the festival, giving the details of the sacrifices offered by Abraham, his wife Hager and their son Ishmael. Returning by a different route and singing the praise of Almighty Allah, Muslim worshippers return home and slaughter their animals. On Eid day, Muslims recite the praise of Allah in the following words:

Allah ho Akbar, Allah ho Akbar
La illaha illa Allah, wa Allah ho Akbar, Allah ho Akbarwa 
Lillah hil Hamd 

Translation:Allah is the Greatest, Allah is the Greatest
There is none worthy of worship except Allah and
Alah is the Greatest, Allah is the Greatest and
All praise belongs to Allah 

The person who offers the sacrifice is allowed to use a portion of the meat, the remainder is distributed among the relatives, friends, neighbors and the poor. The animals my be sacrificed on the day of the Eid or the two days that follow. Millions of animals are slaughtered all over the world on this occasion. The skins of the slaughtered animals are sold and the proceeds given to different charities. 

Philosophy of the Sacrifice:According to the teachings of Islam, the sacrifice of animals is not offered to appease offended deities nor to win their favor as an atonement of sins as was the case of many other nations. The Holy Quran made it quite clear by stating:"Neither the flesh nor the blood of your sacrifices reaches God, but it is the righteous motive underlying them that reaches Him." (22:37) In other words, the slaughtering of animals is a symbolic expression whereby a Muslim declares his readiness to lay down his own life and everything he owes for the sake of God Almighty. The animal that is sacrificed really stands for the animal in man himself.