Ahl al- Bait (Arabic أهل البيت, the people of the house ' ) is the name for the family of the Islamic prophet Muhammad. Who is counted for exactly this revered group of people, varies due to different traditions, schools and denominations; the relevant point Koran (Sura 33, verse 33) is open to various interpretations. Today include at least all the wives of the Prophet, his daughter Fatima, her husband Ali ibn Abi Talib and the sons of this union, Hasan and Husain for the Sunnis to the Ahl al -Bayt, but the membership limit was also already drawn much more generous. For the Shia, for the Prophet's family ( mainly because of the Imamate ) plays a prominent role, this group of people, however, is rather limited. You expect next Mohammed only Fatima, Ali, Hasan and Husain - ie the Ahl al - Kisa ( by a known tradition, the Hadith al - Kisa ) - and their direct descendants of the Ahl al -Bayt. After imamitischem faith, these are the core to the " Fourteen Infallibles ".
In the Zaydi and the Mu ʿ taziliten the consensus of the Ahl al -Bayt was considered pretty powerful argument. The Zaydi imams considered their case as Ahl al -Bayt.