Over a hundred thousand Muslims accompanied Prophet Muhammad (PBUH) in his way back from his last pilgrimage to Mecca when Gabriel ascended to him in the Ghadir Khum with three messages: "O Prophet! Declare what you were commanded to"; "Your Prophetic mission is not incomplete unless you declare the order of God"; "God protects you from the malevolent". Hence, the occasion is known as Feast of Ghadir Khum or Ghadir.
On the basis of the above messages, Ghadir was the planning point for Imamate organization and is a pledge to continue the path of the Prophet (PBUH) and the infallibles. The Ghadir occasion is the day to reread the record of Imamate and Velayat.
The holy Prophet clearly announced: Ali is the leader of those whom I am a leader.
The enemies of Ghadir are not only the enemies of Ali but also the enemies of guidance of mankind. The Ghadir is not only an occasion when the successor of Prophet Muhammad (PBUH) was appointed but also the successors to Imam Ali were also appointed by the Prophet (PBUH).
After introduction of the first successor, the Prophet (PBUH) also introduced his last successor so the believers may not lose the path and all know that there will be twelve of his successors who are all his Caliphs. The last of them rises to expand justice and revive the religion of God all over the world.
It is clear therefore that the Holy Prophet (PBUH) not only appointed Imam Ali as his successor, but also drew the line of Imamate so that the Muslims would follow his proper line through these infallible personalities.
source : www.tebyan.net
