Listen to the “Father Of The Wahhabi’s” alayhi rahmatallah:

In his book while he was answering to question regarding person, who doesn’t consider Ali as a part of ahlelbayt, sheikhul Islaam said:

As for Ali being the part of ahlelbayt, that is from things regarding which there is no contradiction between Muslims. And that is so apparent between Muslims, that need no proof. More than this, he is best from ahlalbayt, and best from bani Hashim after the messenger of Allah (sallalahu alaihi wa sallam). And it’s proven from messenger of Allah (salallalahu alaihi wa sallam) that he put his cloak upon Ali, and Fatima, and Hasan and Husayn and said: “O Allah, these are my ahlelbayt, take away from them impurity, and purify them with a thorough purification”.

Source: “al-Fatawa al-Kubra” volume 1, p 55, masalah – 5 – 5.
Darul Kutub al-Ilmiyah. Thk: Mustafa Abdulqader Ata and Muhammad Abdulqader Ata.