Muslim pilgrims walk to cast their stones at a pillar symbolising the stoning of Satan during the annual haj pilgrimage in Mina, Saudi Arabia August 13, 2019. Millions of haj pilgrims began heading back to Mecca for final prayers on Tuesday as the world's largest annual gathering of Muslims wound down without incident despite the logistical challenges and escalating regional tensions. REUTERS/Umit Bektas

Muslim pilgrims circle the Kaaba and pray at the Grand mosque at the end of their Haj pilgrimage in the holy city of Mecca, Saudi Arabia August 13, 2019. Picture taken August 13, 2019. Senior officials said there had been no major incidents and the logistical, security and health plans had been successful, even with some heavy rainfall. REUTERS/Umit Bektas

Muslim pilgrims circle the Kaaba and pray at the Grand mosque at the end of their Haj pilgrimage in the holy city of Mecca, Saudi Arabia August 13, 2019. Picture taken August 13, 2019. Saudi Arabia stakes its reputation on its guardianship of Islam's holiest sites, Mecca and Medina, and its organisation of the pilgrimage. It hopes to continue expanding attendance to help to build its tourism industry. REUTERSUmit Bektas

Muslim pilgrims walk to cast their stones at a pillar symbolising the stoning of Satan during the annual haj pilgrimage in Mina, Saudi Arabia August 13, 2019. Pilgrims participated in a symbolic stoning of the devil, part of the haj rituals, in Jamarat before returning to Mecca, where the Grand Mosque filled with worshippers preparing to depart. REUTERS/Umit Bektas

Muslim pilgrims circle the Kaaba and pray at the Grand mosque at the end of their Haj pilgrimage in the holy city of Mecca, Saudi Arabia August 13, 2019. Picture taken August 13, 2019. Millions of haj pilgrims began heading back to Mecca for final prayers on Tuesday as the world's largest annual gathering of Muslims wound down without incident despite the logistical challenges and escalating regional tensions. REUTERSUmit Bektas

An aerial view of Kaaba at the Grand mosque in the holy city of Mecca, Saudi Arabia August 12, 2019. Senior officials said there had been no major incidents and the logistical, security and health plans had been successful, even with some heavy rainfall. REUTERS/Umit Bektas