Messenger of Allah ﷺ said, "The example of the person who knows the Qur'an by heart is like the owner of tied camels. If he keeps them tied, he will control them, but if he releases them, they will run away." (Using translation from Bukhārī 5031)
أَنَّ رَسُولَ اللهِ ﷺ قَالَ إِنَّمَا مَثَلُ صَاحِبِ الْقُرْآنِ كَمَثَلِ صَاحِبِ الْإِبِلِ الْمُعَقَّلَةِ فَإِنْ تَعَاهَدَهَا أَمْسَكَهَا وَإِنْ أَطْلَقَهَا ذَهَبَتْ