Parable of the one who memorises the Holy Quran and then retains it

عَنِ ابْنِ عُمَرَ رضى الله عنهما أَنَّ رَسُول الله صلّى الله عليه وسلّم قَالَ إِنَّمَا مَثَلُ صَاحِبِ الْقُرْآنِ كَمَثَلِ صَاحِبِ الإِبِلِ الْمُعَقَّلَةِ إِنْ عَاهَدَ عَلَيْهَا أَمْسَكَهَا وَإِنْ أَطْلَقَهَا ذَهَبَتْ.‏  

Hazrat Ibn ‘Umar^ra narrated: 

“Allah’s Messenger^sa said, ‘The likeness of the one who has memorised the Quran is that of a man with camels that are tethered: if he keeps up his care for them, he retains them; but if he lets them go, they slip away.’”

(Sahih al-Bukhari, Kitab fada’ili l-qur’an, Bab istidhkari l-qur’ani wa ta‘ahudih, Hadith 5031)