Muslims around the world are celebrating the festival of Eid al-Adha, including more than two million pilgrims taking part in annual Hajj rituals in Saudi Arabia.

Pilgrims in the Saudi holy city of Mecca threw stones at three pillars representing Satan, a ritual that began Friday and continues until Sunday.  No major incidents were reported Friday, the third day of the pilgrimage.

But on Saturday, Saudi authorities reported that a 70-year old Pakistani man taking part in the Hajj had died of the H1N1 swine flu virus.  He is the fifth pilgrim to die of swine flu since the days leading up to the pilgrimage.  Experts have warned that swine flu could spread among pilgrims.

Eid al-Adha, or "Festival of Sacrifice," is considered one of the most important days on the Islamic calendar.  Muslims mark the festival by slaughtering cattle to commemorate a belief that God gave the prophet Abraham a ram to sacrifice in place of his son.

On Friday, Sheikh Osman Khayat delivered a sermon before thousands of pilgrims at Mecca's Grand Mosque.  He called for unity among Muslims and condemned divisions that he said were provoked by enemy forces.

The Hajj is one of Islam's five obligations, or pillars.  Every Muslim, if able, must perform it at least once during his or her lifetime.

Some information for this report was provided by AFP and Reuters.