عَنْ أَبِي مُوسَى الْأَشْعَرِيِّ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «تَعَاهَدُوا الْقُرْآنَ فَوَالَّذِي نَفْسِي بِيَدِهِ لَهْوَ أَشَدُّ تَفَصِّيًا مِنَ الْإِبِلِ فِي عُقُلِهَا»

Abū Mūsā al-Ash’arī reported God’s messenger as saying, “Keep refreshing your knowledge of the Qur’ān, for I swear by Him in whose hand my soul is that it is more liable to escape than camels which are tethered.” (Bukhārī and Muslim.)