The pilgrims started their way for Mina by road, by train or on foot on Sunday in a bid to pray and rest before moving on to Mount Arafat on Monday for the climax of the pilgrimage rituals.
The men are required to wear the seamless two-piece garment and the women should cover up themselves, except faces and hands.
More than 100,000 troops have been deployed to Mecca to ensure the safety of the pilgrims.
The number has been reduced by about one million since last year, over fears of outbreak of a deadly virus, known as MERS, as well as construction projects in Mecca.
All the pilgrims who enter Mecca should undertake a minor Hajj before performing their major Hajj, which began on October 13.
The major Hajj is performed during a five-day period from the 8th through the 12th of Dhu al-Hijjah, the last month of the Muslim lunar calendar.
The Hajj pilgrimage is obligatory for all Muslims once in their lifetime if they are able both physically and financially. The teachings of Hajj are also very significant. Muslims remember that they are not joined together on the basis of color or race, but on the basis of belief in God and His messenger.