English Lecture:

https://www.youtube.com/watch?v=LotcQrWhpOo&feature=related

The Prophet Muhammad said:"Behold!  The similitude of members of my family, Ahlul Bayt, is like that of the Ark of Noah:The one who embarks it, will have saved himself, and the one who turns away from it, is doomed".
(See Mustadrak, Al-Haakim, Vol. 3, Page 151.)

The messenger of Allah (PBUH&HF) said: "I am leaving for you two precious and weighty Symbols that if you adhere to BOTH of them you shall not go astray after me. They are, the Book of Allah, and my progeny, that is my Ahlul-Bayt. The Merciful has informed me that These two shall not separate from each other till they come to me by the Pool (of Paradise)."

Sahih al-Tirmidhi, v5, pp 662-663,328, report of 30+ companions, with reference to several chains of transmitters.
al-Mustadrak, by al-Hakim, Chapter of "Understanding (the virtues) of Companions, v3, pp 109,110,148,533 who wrote this tradition is authentic (Sahih) based on the criteria of the two Shaikhs (al-Bukhari and Muslim).

Read More About the Ahlul-Bayt (a):
http://islamicbooks.info/H-21-Math'habs/Prophet-Ahlul-7.htm#_ftn3