The angel Gabriel came to Muhammad every year to read the Qur'an with him, but this year he came twice. Muhammad understood this as his time was coming to an end, and thus told his close followers to call all people from various places to join him in his final pilgrimage to Mecca. This occasion marked the first time that Muslims of this number had gathered in one place in the presence of their leader. It has been reported that more than seventy thousand people followed him to Mecca and that on the fourth day of Dhu'l-Hijjah, more than one hundred thousand Muslims had entered Mecca.
It was during this pilgrimage that he declared the validity of the Mut'ah of Hajj.
The Farewell Sermon
Muhammad led the Pilgrims from Mecca through the Valley of Mina and up to the Mountain of Arafat and then stopped them in the Valley of Uranah. They stood in front of him silently as he sat on his camel and delivered his farewell sermon.
Shi'a clams that It was first after the departure that the events of Ghadir Khumm took place where the hadith of the two weighty things and Hadith of the pond of Khumm were reported. These are a point of controversy among Sunnis and Shi'a. According to the latter this is where he appointed Ali as his successor and asked the present muslims to pledge allegiance to the future leader.
- O Apostle! deliver what has been revealed to you from your Lord; and if you do it not, then you have not delivered His message, and Allah will protect you from the people; surely Allah will not guide the unbelieving people.
Some Sunnis view it was revealed during this Pilgrimage, while some other Sunnis and the Shi'a view it was revealed just prior to the Ghadir Khumm event.