AHL AL BAYT
إِنَّمَا يُرِيدُ اللَّهُ لِيُذْهِبَ عَنكُمُ الرِّجْسَ أَهْلَ الْبَيْتِ وَيُطَهِّرَكُمْ تَطْهِيرًا
“…Allah only desires to keep away the uncleanness from you, O people of the House! and to purify you a (thorough) purifying….” (Quran 33:33)
The Ahl al Bayt is the household of the Prophet Muhammad S.A.W. who have inspired and guided the Muslim community after his demise.
Household here means the nearest relatives referring to his daughter Fatima az-Zahra, his son-in-law and successor Imam Ali A.S., their two son Imam Hasan and Imam Husayn and the nine Imams from the lineage of Imam Husayn.
The Messenger of Allah (S) in his well-attested tradition said:
“Verily, I leave behind amongst you two precious things: the Book of Allah, the Almighty and the Glorious, and my kindred (`Itrah). The two will never be separate until they return to me by the Pond.”
Here is a link to literature on Ahl al Bayt.