O People of Scripture! Do not be extreme in your religion! [Al-Mâ`idah (5): 77]
It is reported from Qatâdah – Allâh have mercy on him – that he said, commenting on this verse, “Meaning: do not innovate in religion and do not sit with a religious innovator (mubtadi’).”
Ibn Battah, Al-Ibânah Al-Kubrâ Vol.1 p394.