The phrase Ahl Al-Bayt denotes the Prophet’s Muhammad family, household, progeny or infallible. Literally, Ahl Al-Bayt means “the dweller of the house.”
According to the Shiite Muslims, Twelvers, Ahl Al-Bayt are infallible who should be respected, loved and obeyed because of the purification verse in the holy Book, Quran, refers to them. In this regard, Ahl Al Bayt headed by Prophet Muhammad (PBUH), his daughter Fatima and the twelve Imams.
Under the umbrella of Ahl Al Bayt, there is another related term Ahl al-Kisa (‘family of the cloak’). This term denotes Prophet Muhammad (PBUH), his daughter Fatima, her husband Imam Ali and their sons Imam Al-Hasan and Imam Al-Hussein. This term has emerged from a historical incident when a delegate from Najran ( the infallibles area on Yemen-Saudi border) visited Prophet Muhammad (PBUH) to argue that he is not a Prophet. As a result, Prophet Muhammad (PBUH) suggested an idea to resolve this dispute between him and the delegate through asking the Creator, Almighty, by each party, to curse the liars. In his regard, Prophet Muhammad (PBUH) brought the infallible and covered them with a cloak. When the delegate saw Prophet’s Muhammad (PBUH) and his infallibles, they stopped their argumentation and refrained from proceeding in the cursing process.