The world's 1.5 billion Muslims marked the start of Eid al-Adha, or the feast of sacrifice on Monday, while in Saudi Arabia nearly 2 million pilgrims performed one of the final rites of the hajj by symbolically stoning the devil.

Muslims celebrate Eid al-Adha to commemorate Ibrahim's, or Abraham's, test of faith in God. They believe Ibrahim committed to kill his only son Ismail on the command of God.

Having tested Ibrahim's faith, God sent a lamb in the boy's place.

During the holiday, which ends Thursday, Muslims slaughter sheep or goats to share with family, friends and the needy.

Eid al-Adha coincides with the final days of the hajj pilgrimage in and around the holy city of Mecca, Saudi Arabia.

In one of the final rituals in Mina, outside Mecca, pilgrims pelted three large stone columns with pebbles on Monday in a symbolic stoning of the devil.

The Jamarat ritual, which will continue on Tuesday, emulates Ibraham's stoning of the devil in resisting the temptation to disobey God's command.

One of the five pillars of Islam holds that every financially and physically capable Muslim must participate in the hajj at least once in life. Muslims also visit Mecca outside of the annual period of the hajj in what is known as performing "umrah."

During the five-day-long hajj, pilgrims go through a number of rituals tracing the footsteps of the Prophet Muhammad and the prophets Ibrahim and Ismail.

It starts with pilgrims circling around the cube-shaped Kaaba, Islam's holiest site towards which Muslims around the world pray.

cw/gsw (AFP, AP, Reuters)