It is narrated in Sahih Muslim as well as many other sources that:
Someday (after his last pilgrimage) the Messenger of Allah (PBUH)
stood to give us a speech beside a pond which is known as Khum
(Ghadir Khum) which is located between Mecca and Medina. Then
he praised Allah and reminded Him, and then said: “O’ people!
Behold! It seems the time approached when I shall be called away
(by Allah) and I shall answer that call. Behold! I am leaving for you
two precious things. First of them is the book of Allah in which there
is light and guidance… The other one is my Ahlul-Bayt. I remind
you in the name of Allah about my Ahlul-Bayt. I remind you in the name of Allah about my Ahlul-Bayt. I remind you in the name of
Allah about my Ahlul-Bayt. (three times).”
Sunni Reference:
- Sahih Muslim, Chapter of the virtues of the companions, section of the virtues of Ali, 1980 Edition Pub. in
Saudi Arabia, Arabic version, v4, p1873, Tradition #36. - And many others such as Sahih al-Tirmidhi, Musnad Ahmad (see below).
For the English version of Sahih Muslim, see Chapter CMXCVI, v4, p1286, Tradition #5920
Aal-e-Qutub Aal-e-Syed Abdullah Shah Ghazi 