All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
The source of Islamic knowledge is only the Quran and the Sunnah (Prophetic tradition) of the Prophet Muhammad . The Ahlul-Bayt (family of Prophet Muhammad ) have never been used as a source for Islamic teachings. Imaam Al-Bukhari and Muslim reported from ‘Ali that the Prophet delivered a sermon saying:
"We have no book to read except the Book of Allaah and what is written in this paper which contains verdicts regarding (retaliation for) wounds, the ages of the camels [given as Zakat (obligatory charity) or as blood money] and the fact that Madeenah is a sanctuary in between Air mountain to so-and-so (mountain). So, whoever innovates in it a heresy or commits a sin or gives shelter in it, to such an innovator will incur the curse of Allaah, the angels and all the people, and none of his compulsory or optional good deeds of worship will be accepted. And whoever (i.e., a freed slave) takes as his master (i.e., befriends) other than his real masters will incur the same (curse). And the asylum granted by any Muslim is to be secured by all the other Muslims, and whoever betrays a Muslim in this respect will incur the same (curse)."
Once Abu Juhayfah asked ‘Ali "Did the Prophet reserve something for your family other than what was given to all Muslims?" He said, “By Allaah, we have nothing except the book of Allaah and this written paper from the Prophet ” then he opened the paper which contained verdicts regarding (retaliation for) wounds and the ages of the camels (to be paid as Zakah).
These narrations prove that ‘Ali himself denied that they (the Ahlul-Bayt) had any special knowledge which is not known to others. What is known from ‘Ali, Al-Hasan, Al-Husayn and Faatimah, the daughter of the Prophet is that they were always keen on following the Quran and Sunnah and nothing else – all. There are many known good virtues of the Ahlul-Bayt the family of the Prophet Muhammad ; one may find recorded them in the authentic books.
There is some disagreement among the scholars regarding the persons who are called Ahlul-Bayt. The preponderant opinion in the light of Quran and Sunnah is that Ahlul-Bayt means ‘Ali, Faatimah, Al-Hasan, Al-Husayn and the wives of the Prophet Muhammad .
Allaah Knows best.