Starting at dawn, the more than 1.6 million Muslims taking part in the pilgrimage will throw seven stones at each of three concrete walls symbolising the devil in the Mina valley, on the outskirts of the holy city of Mecca.

The ritual commemorates Abraham’s stoning of the devil at the three spots where it is said Satan tried to dissuade him from obeying God’s order to sacrifice his son.

This year’s haj saw authorities implementing a range of heat mitigation efforts alongside a wide-ranging crackdown on illicit pilgrims – resulting in noticeably thinner crowds and a heavy security presence at holy sites in Mecca and surrounding areas.

The measures were aimed at preventing a fatal repeat of last year’s haj that saw 1,301 people die in temperatures that hit 51.8°C.

Saudi authorities said a majority of those deaths were among pilgrims who illegally snuck into Mecca and lacked access to accommodation and other services aimed to keep pilgrims safe and protected from the searing desert heat.

Haj permits are allocated to countries on a quota basis and distributed to individuals by a lottery system.

But even for those who can secure them, the high costs spur many to attempt the haj without a permit, even though they risk arrest and deportation if caught.

The stoning ritual in the Mina valley was the scene of a fatal stampede in 2015, when 2,300 people were killed in one of the deadliest haj disasters.

Saudi Arabia earns billions of dollars a year from the haj, and the lesser pilgrimage known as umrah, undertaken at other times of the year.

The pilgrimages are also a source of prestige for the Saudi monarch, who is known as the Custodian of the Two Holy Mosques of Mecca and Medina.

The end of the haj coincides with the beginning of Eid al-Adha – an annual feasting holiday marked by the slaughter of an animal – typically a goat, sheep, cow, bull or camel.