Some 1.4 million Islamic pilgrims are beginning the hajj in Saudi Arabia.
Pilgrims from 160 countries began on October 2 to move from the city of Mecca to nearby Mina Valley by road, train, or on foot to start the annual pilgrimage.
In Mina, pilgrims will pray and rest before moving on to Mount Arafat on October 4 for the culmination of the pilgrimage rituals.
The hajj is one of the five pillars of Islam that every capable Muslim must perform at least once in their life.
Safety and security measures have reportedly been stepped up amid concerns about terrorism, especially following the rise of the Islamic State extremist group this year, and disease.
Health officials have been battling the MERS respiratory virus and are also on alert for the Ebola virus, which has killed more than 3,000 people across West Africa.