Shaykh Ahmad al-Tijani (God be pleased with him) said:

We have a foundational principle on which all other principles are based: Judgement belongs to naught but God and His Messenger, and no consideration shall be given to any legal ruling except what is [supported] by the words of God and His Messenger (God bless him and give him peace); and it is unlawful (haram) to give a legal verdict (fatwa) on the basis of any view from a scholar that contravenes the explicit [verses] of the unequivocal Quran and the explicit words of the Messenger of God (God bless him and give him peace)—even if said opinion has found its way into the books of jurisprudence. That is because giving a legal verdict on the basis of a view contradicting the unequivocal verses of the Quran or the unequivocal hadith reports is clear-cut disbelief when such [contradiction] is known. God—Exalted and Sublime is He—says, “Whosoever does not judge by what Allah has revealed, they are the disbelievers.” (Quran 5:44) And the Prophet (God bless him and give him peace) said, “Whosoever innovates into this matter of ours [religion] what is not from it, it is rejected.”…

~Jawahir al-Ma’ani