Clutching the pebbles collected on their way overnight from the town of Muzdalifah, the flock of pilgrims started arriving in Mina early in the morning as the city's roads choked with people making their way to their camps.
Large crowds began the rite in which pillars symbolising the Satan are stoned as a mark of the believers' resistance to the devil. The ritual will continue for two more days as the pilgrims complete their pilgrimage.
The faithful also sacrificed animals today to mark Prophet Abraham's sacrifice of his son Ismail in the name of God, as Muslims celebrated Eid al Adha in several parts of the world.
The five-day rituals of Hajj began on October 24 when millions arrived in the holy city of Mecca.
They travel from Mecca to the nearby city of Mina to spend a night in prayer and spend time near Mount Arafat before performing the symbolic ritual of devil stoning.
The stay on Arafat where Prophet Mohammad delivered his last sermon is the most important ritual of the pilgrimage and was performed by nearly 3 million pilgrims including 1.7 lakh from India.
Mount Arafat is also known as Jabal Al Rahm or 'Mountain of Mercy'.
A white sea of humanity in seamless white robes assembled on Arafat with the chant of 'Labbaik Allahumma Labbaik' (Here I am O God, answering your call).
As the faithful spent the day praying for mercy and forgiveness, and contemplating on their lives, many were seen in tears.
"I really can't describe the feeling of being here at Arafat for the first time. It is overwhelming," 63-year-old Rayees Nomani, from Lucknow, was quoted as saying by Arab News.
Hajj is one of the five pillars of Islam and every able bodied Muslim who can afford to travel to Mecca is expected to perform the pilgrimage at least once in his or her lifetime.