وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏"‏ إِنَّمَا مَثَلُ صَاحِبِ الْقُرْآنِ كَمَثَلِ صَاحِبِ الإِبِلِ الْمُعَقَّلَةِ إِنْ عَاهَدَ عَلَيْهَا أَمْسَكَهَا وَإِنْ أَطْلَقَهَا ذَهَبَتْ ‏"‏ ‏.‏

Yahya related to me from Malik from Nafi from Abdullah ibn Umarthat the Messenger of Allah, may Allah bless him and grant him peace,said, "A man who knows the Qur'an well is like a man who has a hobbledcamel. If he takes care of it, he keeps it, and if he lets it go, itgets away." Translation Not Available

Book reference: Muwatta Imam Malik Book 15 Hadith 478
Web reference: Muwatta Imam Malik Book 15 Hadith 6