The haj pilgrimage is set to begin on Tuesday, with more than 1.3 million people having already arrived in Saudi Arabia and up to three million people expected to visit the holy site in Mina, Mecca, over five days.
The pilgrims will stream into Mina on Tuesday ahead of the Day of Arafat on Wednesday, the ninth day of Dhu Al Hijja, which is the last month of the Islamic lunar calendar.
On the Day of Arafat, Muslims will traverse 20 km from Mina to Mount Arafat just outside Mecca, to stand at the site where Prophet Mohammed is believed to have delivered his farewell sermon.
The Day of Arafat is observed a day before Eid al Adha, which will be celebrated on Thursday in Saudi Arabia and many other countries.
The pilgrims will also perform Tawaf, wherein they will circumambulate the Kaaba seven times as part of the rituals of the pilgrimage.
Performing the haj is one of the five pillars of Islam and every Muslim is expected to go on the pilgrimage at least once.
As many as 1,372,148 pilgrims arrived in the kingdom till Saturday, Saudi Gazette reported. The number of pilgrims from outside and within the kingdom is expected to reach three million over the five days of the pilgrimage.
Saudi Arabia has deployed 100,000 security personnel for the haj pilgrimage, including troops from the army and National Guard.
Around 5,000 CCTV cameras will help officials keep a watch over the massive crowds to ensure safety, as concerns have gripped Haj 2015 following several terror attacks in Saudi Arabia in recent months.
"The security forces are ready to confront any irresponsible behaviour that might pollute the purity of haj or endanger the lives of the guests of Allah," interior minister and crown prince Mohammed bin Nayef was quoted as saying by state media.
What has further marred the religious pilgrimage is the deadly crane crash more than a week ago, which killed over 100 pilgrims.
Another concern for authorities and pilgrims is the MERS outbreak in the kingdom, and worries remain despite the government's assurance that cases have been on the decline.