Muslim pilgrims pray on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Tuesday, Sept. 22, 2015. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite. Muslim pilgrims pray on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Tuesday, Sept. 22, 2015. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite. Muslim pilgrims pray on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Tuesday, Sept. 22, 2015. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
A Muslim pilgrim prays on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Tuesday, Sept. 22, 2015. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
Muslim pilgrims pray on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Tuesday, Sept. 22, 2015. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
A Muslim pilgrim prays on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Wednesday, Sept. 23, 2015 during the hajj pilgrimage. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
Muslim pilgrims pray on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Wednesday, Sept. 23, 2015 during the hajj pilgrimage. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
A Muslim pilgrim prays on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Wednesday, Sept. 23, 2015 during the hajj pilgrimage. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
Muslim pilgrims pray on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Wednesday, Sept. 23, 2015. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
Muslim pilgrims pray on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Wednesday, Sept. 23, 2015 during the hajj pilgrimage. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
Muslim pilgrims pray on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Wednesday, Sept. 23, 2015 during the hajj pilgrimage. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
Muslim pilgrims pray on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Wednesday, Sept. 23, 2015 during the hajj pilgrimage. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
Muslim pilgrims pray underneath a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Wednesday, Sept. 23, 2015 during the hajj pilgrimage. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
Muslim pilgrims pray on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Wednesday, Sept. 23, 2015 during the hajj pilgrimage. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
Muslim pilgrims pray on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Wednesday, Sept. 23, 2015 during the hajj pilgrimage. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
Muslim pilgrims pray on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Wednesday, Sept. 23, 2015 during the hajj pilgrimage. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
Muslim pilgrims arrive by bus to Arafat to pray on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Wednesday, Sept. 23, 2015 during the hajj pilgrimage. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
A child crawls outside his family's tent as prepare to pray on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Wednesday, Sept. 23, 2015. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
A pilgrim reads the Muslim holy book, Quran, on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Wednesday, Sept. 23, 2015. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
Muslim pilgrims climb a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Wednesday, Sept. 23, 2015 during the hajj pilgrimage. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
Muslim pilgrims pray on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Wednesday, Sept. 23, 2015 during the hajj pilgrimage. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.
A Muslim pilgrim prays on a rocky hill called the Mountain of Mercy, on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia, Wednesday, Sept. 23, 2015 during the hajj pilgrimage. Mount Arafat, marked by a white pillar, is where Islam's Prophet Muhammad is believed to have delivered his last sermon to tens of thousands of followers some 1,400 years ago, calling on Muslims to unite.