As Muhammad was returning from his last pilgrimage in 632, he made statements about Ali that are interpreted very differently by Sunnis and Shias.
He halted the caravan at Ghadir Khumm, gathered the returning pilgrims for communal prayer and began to address them.

According to the Encyclopedia of Islam:
Taking Ali by the hand, he asked of his faithful followers whether he, Muhammad, was not closer (awlā) to the Believers than they were to themselves; the crowd cried out: "It is so, O Apostle of God!";
he then declared: "He of whom I am the mawla, of him Ali is also the mawla (man kuntu mawlāhu fa-ʿAlī mawlāhu)".

Shias regard these statements as constituting the designation of Ali as the successor of Muhammad and as the first Imam; by contrast, Sunnis take them only as an expression of close spiritual relationship between Muhammad and Ali, and of his wish that Ali, as his cousin and son-in-law, inherit his family responsibilities upon his death, but not necessarily a designation of political authority.

 Many Sufis also interpret the episode as the transfer of Muhammad's spiritual power and authority to Ali, whom they regard as the wali par excellence.

Sources, among them both Shia and Sunni, state that, after the sermon, Abu Bakr, Umar, and Uthman pledged allegiance to Ali.
However, there have been doubts regarding the veracity of the tradition due to evidence that Ali may not have been present during the sermon, instead being in Yemen at the time—a view held by the historian Ibn Kathir.
As Muhammad was returning from his last pilgrimage in 632, he made statements about Ali that are interpreted very differently by Sunnis and Shias. He halted the caravan at Ghadir Khumm, gathered the returning pilgrims for communal prayer and began to address them.
According to the Encyclopedia of Islam:
Taking Ali by the hand, he asked of his faithful followers whether he, Muhammad, was not closer (awlā) to the Believers than they were to themselves; the crowd cried out: "It is so, O Apostle of God!"; he then declared: "He of whom I am the mawla, of him Ali is also the mawla (man kuntu mawlāhu fa-ʿAlī mawlāhu)".
Shias regard these statements as constituting the designation of Ali as the successor of Muhammad and as the first Imam; by contrast, Sunnis take them only as an expression of close spiritual relationship between Muhammad and Ali, and of his wish that Ali, as his cousin and son-in-law, inherit his family responsibilities upon his death, but not necessarily a designation of political authority.
 Many Sufis also interpret the episode as the transfer of Muhammad's spiritual power and authority to Ali, whom they regard as the wali par excellence.
Sources, among them both Shia and Sunni, state that, after the sermon, Abu Bakr, Umar, and Uthman pledged allegiance to Ali. However, there have been doubts regarding the veracity of the tradition due to evidence that Ali may not have been present during the sermon, instead being in Yemen at the time—a view held by the historian Ibn Kathir.
Ali