According to most authentic traditions in collections of both Sunni and Shi’a, Ahlul-Bayt (People of the House) of the Prophet are one of the two most precious Symbols of Islam after the departure of the Prophet (S). There are numerous traditions in the collection of both schools that the Prophet (S) has reminded us to stick to these two weighty things (al-Thaqalain), namely Qur’an and Ahlul-Bayt, in order not to go astray after him.
The Messenger of Allah also informed us that these two weights are non-separable and are with each other till the day of Judgment. This requires us that for understanding the interpretation of Qur’an and the Sunnah of the Prophet (S) we should refer to those who are attached to it, namely Ahlul-Bayt.
Knowing exactly who Ahlul-Bayt are, thus becomes a very vital matter when one considers the above tradition of the Prophet (S) as well as many other traditions which unequivocally state that adherence to Ahlul-Bayt is the only way of salvation. This clearly implies that the one who follows a wrong set of Ahlul-Bayt (!!), will be led astray.
To the Shi’a, the Ahlul-Bayt of the Prophet (S) consist of the following individuals ONLY:
• Fatimah al-Zahra (sa),
• Imam ‘Ali (as),
• Imam al-Hasan (as),
• Imam al-Husayn (as),
• Nine descendants of Imam al-Husayn (as).
and including the Prophet (S) himself, they will become fourteen individuals. Of course, at the time of the Holy Prophet only five of them (including the Prophet) were living and the rest were not born yet.
The Shi’a further assert that these fourteen individuals are protected by Allah from any kind of flaws, and thus worthy of being obeyed beside Qur’an (the other Weighty Symbol), and they are the only people who have the full knowledge of the interpretation of the Qur’anic verses.