Some two million Muslim pilgrims gathered in the valley of Mount Arafat in Saudi Arabia for a day of prayer that marks the pinnacle of the annual hajj.

Pilgrims stood shoulder to shoulder for an emotional day of repentance and supplication at the site where Muslims believe the Prophet Mohammed delivered his final sermon, calling for equality and for Muslims to unite.

According to the hadiths, traditional collections of the prophet’s sayings and anecdotes about his life, Mohammed also reminded his followers of women’s rights and that every Muslim life and property is sacred.

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An elderly Muslim pilgrim walks with her daughter to their bus (Dar Yasin/AP)

Muslims believe prayer on this day at Mount Arafat, about 12 miles east of the holy city of Mecca, is their best chance to erase past sins and start anew.

Around sunset on Monday, pilgrims will head to an area called Muzdalifa, which is 5.5 miles west of Arafat.

Many walk, while others use buses.

They spend the night there and pick up pebbles along the way that will be used in a symbolic stoning of the devil back in the city of Mina, where Muslims believe the devil tried to talk Ibrahim out of submitting to God’s will.

The kingdom has spent billions of dollars of its vast oil revenues on security and safety measures, particularly in Mina, where some of the hajj’s deadliest incidents have occurred.

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Muslim pilgrim prepare to get on the bus (Dar Yasin/AP)

The worst in recorded history took place only three years ago.

On September 24 2015, a stampede and crush of pilgrims in Mina killed at least 2,426 people, according to an Associated Press count.

The official Saudi toll of 769 people killed and 934 injured has not changed since only two days after the tragedy.

The kingdom has never addressed the discrepancy in the casualty toll, nor has it released any results of an investigation that authorities had promised to conduct over the disaster.

The five-day hajj pilgrimage represents one of the world’s biggest gatherings every year, and is required of all able-bodied Muslims once in their life.

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Muslim pilgrims along with their belongings walks towards Namirah mosque on Arafat Mountain (Dar Yasin/AP)

At the hajj’s end, male pilgrims will shave their hair and women will cut a lock of hair in a sign of renewal for completing the pilgrimage.

Around the world, Muslims will mark the end of hajj with a celebration called Eid al-Adha.

The holiday, remembering Ibrahim’s willingness to sacrifice his son, sees Muslims slaughter sheep and cattle, distributing the meat to the poor.

Overnight, a sandstorm packing strong winds and thunderstorms roared through Mecca.

Officials say the severe weather slightly damaged some tents housing pilgrims, but caused no injuries.