Ahlul Bayt is a term that signifies the pure descendant of the Holy Prophet of Islam and the Last Messenger, Muhammad s.a.w.a. But the interpretation of the infallibility of Ahlul Bayt is still debated by the two main sect, Sunni and Shiite. For the follower of Shiite Islam, Ahlul Bayt is free from any sins and hold the secret knowledge of Prophet Muhammad s.a.w.a. The Sunni sect on other way, stated that Ahlul Bayt is not free from any sins and Imamate don't delong to them alone.
The difference don't only belong to the merits, the difference can be traced to the definition of who is the People of Holy household by the two main sect. In Sunni Islam, Muhammad's household includes his wives, his daughter (Fatimah), her three children, as well as his cousin and son-in-law, Ali. The Shi'a definition of the phrase includes only Fatimah, Ali, Hasan and Husayn (known collectively as the Ahl al-Kisa, "people of the mantle") and the Imams, descendants of Fatimah who they consider to be divinely chosen leaders of the Muslim community.
The Lover of Ahlul Bayt is the one who practice salawat daily and follow the teachings of Ahlul Bayt without any doubt and with certitude. They don't care if they are being threaten by death for their love because they know the essence of this love is pain and sufferation as what is being suffered by their Imams.
The Verse of Purity (Ayat Al-Tathir): "... Allah only desires to keep away the uncleanness from you, O people of the House! And to purify you a (thorough) purifying." Noble Qur'an (33:33)
It is narrated from Umm al-Momineen, Umm Salamah that once Prophet Muhammad (pbuh) was in her house lying on a mattress, covered with a cloak from Khaibar when his beloved daughter Fatima Zahra (pbuh) entered with a dish called al-Khazira (a kind of food). Prophet Muhammad (pbuh) asked her to call her husband, Imam Ali and her two sons, Imam Hasan and Imam Hussain. Fatima Zahra (pbuh) called them and as they all sat together to eat, Allah revealed the following verse of purity (Ayat Al-Tathir) to Prophet Muhammad (pbuh). "... Allah only desires to keep away the uncleanness from you, O people of the House! And to purify you a (thorough) purifying." Noble Qur'an (33:33)
Prophet Muhammad - may Allah bestow peace and benedictions upon him and his pure Progeny - said: "Verily, I am leaving behind two precious things (thaqalayn) among you: the Book of Allah and my kindred (itrah), my household Ahlul Bayt (Ahl al-Bayt), for indeed, the two will never separate until they come back to me by the Pond (of alKawthar on the Day of Judgement)." [Hadith-e-Saqlain]
