How to Deal with the People of Innovations: A Collection of Treatises

So we said “O Messenger of Allah! It is as if this is a farewell admonition, so advise us.” He said, “I advise you with the taqwa (fear, reverence) of Allah. And listen and obey, even if the one who is appointed over you in authority is a slave. Indeed, whosoever from amongst you lives after me, then he shall see much differing. So stick to my Sunnah and the Sunnah of the Rightly-Guided Caliphs after me. Hold onto it with your molar teeth and beware of newly invented matters, since every innovation is misguidance.