Ten years after the migration, the Messenger of Allah ordered to his close
followers to call all the people in different places to join him in his
last pilgrimage. On this pilgrimage he taught them how to perform the
pilgrimage in a correct and unified form.

This was first time that the Muslims with this magnitude gathered in one
place in the presence of their leader, the Messenger of Allah. On his way
to Mecca, more than seventy thousand people followed Prophet (pbuh&HF).
On the fourth day of Dhul-Hajjah more than one hundred thousand Muslims
had entered Mecca.
Revelation of Verse 5:67
On the 18th of Dhul-Hajjah, after completing his last pilgrimage (Hajjatul-
Widaa), Prophet was leaving Mecca toward Medina, where he and the crowd of
people reached to a place called Ghadir Khum (which is close to today's
Juhfah). It was a place where people from different provinces should say
Good bye to each other and take different routes for their home. In this
place, the following verse was revealed:

"O Apostle! Deliver what has been sent down to you from your Lord; and
if you don't do it, you have not delivered His message (at all); and
Allah will protect you from the people …" (Quran 5:67).

Some of Sunni references confirming that the revelation of the above verse
of Quran was right before the speech of Prophet in Ghadir Khum:

(1) Tafsir al-Kabir, by Fakhr al-Razi, under commentary of verse 5:67,
v12, pp 49-50, narrated on the authorities of Ibn Abbas, al-Bara Ibn
Azib, and Muhammad Ibn Ali.
(2) Asbab al-Nuzool, by al-Wahidi, p50, narrated on the authorities of
Atiyyah and Abu Sa'id al Khudri.
(3) Nuzul al-Quran, by al-Hafiz Abu Nu'aym narrated on the authorities
Abu Sa'id Khudri and Abu Rafi.
(4) al-Fusool al Muhimmah, by Ibn Sabbagh al-Maliki al-Makki, p24
(5) Durr al-Manthur, by al-Hafiz al-Suyuti, under commentary of verse 5:67
(6) Fathul Qadir, by al-Shawkani, under commentary of verse 5:67
(7) Fathul Bayan, by Hasan Khan, under commentary of verse 5:67
(8) Shaykh Muhi al-Din al-Nawawi, under commentary of verse 5:67
(9) al-Sirah al-Halabiyah, by Noor al-Din al-Halabi, v3, p301
(10) Umdatul Qari fi Sharh Sahih al-Bukhari, by al-Ayni
(11) Tafsir al-Nisaboori, v6, p194
(12) and many more such as Ibn Mardawayh, etc...
The last sentence in the above verse indicates that the Prophet (pbuh&HF)
was mindful of the reaction of his people in delivering that message but
Allah informs him not to worry, for He will protect His Messenger from
The Speech
Upon receiving the verse, the Prophet (pbuh&HF) stopped on that place (the
pond of Khum) which was extremely hot. Then he sent for all people who have
been ahead in the way, to come back and waited until all pilgrims who fell
behind, arrived and gathered. He ordered Salman (ra) to use rocks and camel
toolings to make a pulpit (minbar) so he could make his announcement. It
was around noon time in the first of the Fall, and due to the extreme heat
in that valley, people were wrapping their robes around their feet and
legs, and were sitting around the pulpit, on the hot rocks.

On this day the Messenger of Allah spent approximately five ours in this
place; three hours of which he was on the pulpit. He recited nearly one
hundred verses from The Glorious Quran, and for seventy three times
reminded and warned people of their deeds and future. Then he gave them a
long speech. The following is a part of his speech which has been widely
narrated by the Sunni traditionists:

The Messenger of Allah declared: "It seems the time approached when I
shall be called away (by Allah) and I shall answer that call. I am
leaving for you two precious things and if you adhere both of them,
you will never go astray after me. They are the Book of Allah and my
progeny, that is my Ahlul-Bayt. The two shall never separate from each
other until they come to me by the Pool (of Paradise)."

Then the Messenger of Allah continued: "Do I not have more right over
the believers than what they have over themselves?" People cried and
answered: "Yes, O' Messenger of God." Then Prophet (pbuh) held up the
hand of Ali and said: "Whoever I am his leader (Mawla), Ali is his
leader (Mawla). O' God, love those who love him, and be hostile to
those who are hostile to him."
Some of the Sunni references:
(1) Sahih Tirmidhi, v2, p298, v5, p63
(2) Sunan Ibn Maja, v1, pp 12,43
(3) Khasa'is, by al-Nisa'i, pp 4,21
(4) al-Mustadrak, by al-Hakim, v2, p129, v3, pp 109-110,116,371
(5) Musnad Ahmad Ibn Hanbal, v1, pp 84,118,119,152,330, v4, pp 281,368,370,
372,378, v5, pp 35,347,358,361,366,419 (from 40 chains of narrators)
(6) Fada'il al-Sahaba, by Ahmad Hanbal, v2, pp 563,572
(7) Majma' al-Zawa'id, by al-Haythami, v9, p103 (from several transmitters)
(8) Tafsir al-Kabir, by Fakhr al-Razi, v12, pp 49-50
(9) Tafsir al-Durr al-Manthur, by al-Hafiz Jalaluddin al-Suyuti, v3, p19
(10) Tarikh al-Khulafa, by al-Suyuti, pp 169,173
(11) al-Bidayah wal-Nihayah, by Ibn Kathir, v3, p213, v5, p208
(12) Usdul Ghabah, by Ibn Athir, v4, p114
(13) Mushkil al-Athar, by al-Tahawi, v2, pp 307-308
(14) Habib al-Siyar, by Mir Khand, v1, part 3, p144
(15) Sawaiq al-Muhriqah, by Ibn Hajar al-Haythami, p26
(16) al-Isabah, by Ibn Hajar al-Asqalani, v2, p509; v1, part1, p319,
v2, part1, p57, v3, part1, p29, v4, part 1, pp 14,16,143
(17) Tabarani, who narrated from companions such as Ibn Umar, Malik Ibn
al-Hawirath, Habashi Ibn Junadah, Jari, Sa'd Ibn Abi Waqqas,
Anas Ibn Malik, Ibn Abbas, Amarah,Buraydah,…
(18) Tarikh, by al-Khatib Baghdadi, v8, p290
(19) Hilyatul Awliya', by al-Hafiz Abu Nu'aym, v4, p23, v5, pp26-27
(20) al-Istiab, by Ibn Abd al-Barr, Chapter of word "ayn" (Ali), v2, p462
(21) Kanzul Ummal, by al-Muttaqi al-Hindi, v6, pp 154,397
(22) al-Mirqat, v5, p568
(23) al-Riyad al-Nadirah, by al-Muhib al-Tabari, v2, p172
(24) Dhaka'ir al-Uqba, by al-Muhib al-Tabari, p68
(25) Faydh al-Qadir, by al-Manawi, v6, p217
(26) Yanabi' al-Mawaddah, by al-Qudoozi al-Hanafi, p297