Reference: Fataawa Islaamiyyah – Volume 1, Page 153
Question: Some people consider that it is an obligation upon the Muslim to blindly follow one of the four well known school of Islaamic jurisprudence in order for their acts of worship and their deeds to be correct. Yet the madhhab of the Shee’ah (Raafidhah) is not included amongst them, not even the madhhab of the Zaydee (Zaidi) Shee’ah. Does your eminence agree absolutely with this view, and thus prohibit the blind following of the madhhab of the Shee’ah (Raafidhah), such as the imaamah of the Ithnaa ‘Ashariyyah?
Response: It is an obligation upon the Muslim to follow what came from Allaah and His Messenger (sal-Allaahu ‘alayhi wa sallam), if he is able to infer the legal rulings himself; if he is unable to do so, he should ask the people of knowledge regarding what troubles him in the matter of his religion. He should make inquiries of the most knowledgeable scholar with whom he is able to make contact, so that he may ask him, either in person or in writing.
It is not permissible for the Musim to blindly follow the Shee’ah (Raafidhah) imaamah madhhab, nor the Zaydee (Zaidi) madhhab, nor any other such like madhhab from the people of innovation, such as the Khawaarij, the Mu’tazilah, the Jahmiyyah and others.
As for belonging to one of the four well known madhhaahib, there is no objection to this, so long as he is not a blind follower of the madhhab to which he belongs and does not dispute (authentic) evidence on account of it.
And with Allaah lies all success and may Allaah send prayers and salutations upon our Prophet Muhammad ﷺ and his family and his companions.