The following is from Imam al-Nawawī’s, Etiquette With the Quran:
It is established in Muslim’s Ṣaḥīḥ that Tamīm al-Dārī (God be pleased with him) stated, “The Messenger of God ﷺ said, ‘Religion is sincerity.’ We said, ‘To whom?’ He said, ‘To God, His Book, His Messenger, the leaders of the Muslims, and their common folk.’” The scholars (God grant them mercy) said that having sincerity regarding the Book of God is believing that it is the speech of God Most High and His revelation; that it does not resemble anything from the words of people; and that people are incapable of anything like it even if they all joined together [to attempt it]. [Sincerity is] to extol its glory; recite it and give its recitation its just due—beautifying it, being humble while doing so, and correctly pronouncing its letters. [Sincerity is] defending it from the misinterpretations of the deviators and the opposition of the tyrants; believing in everything that it contains; not exceeding its boundaries; and understanding its knowledge and examples. [It is] paying attention to its exhortations; pondering its amazing wonders; acting according to what has unequivocal meaning; submitting to what is open to interpretation; searching out its universal and restricted [rulings]; its abrogating and abrogated [passages]; and propagating its sciences; and calling others to them and to all the sincere counsel that we have mentioned.