Just a minor correction to the above. The pilgrims must be present on the "Plain of Arafaat" and not on the "Mount" on the Day of Arafaat. After the conclusion of prayers at the Plain of Arafaat, many pilgrims choose to go Mount Arafaat but not all do, and it is not obligatory. I could not make to this mount during Hajj due to the very heavy rush of people but did go there later on when I went for Umrah.