It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that the Messenger of Allah (ﷺ) said: "The example of the one who memorizes the Qur'an is like the owner of a camel whose legs are tied; if he takes care of it, he will keep it, and if he lets it go, it will run away."
Hadith Referenceالسنن المأثورة / باب ما جاء في الصلاة على الراحلة / 103
Hadith Takhrijصحیح بخاری، فضائل القرآن، باب استذكار القرآن و تعاهده، رقم : 5031، صحیح مسلم، المساجد ومواضع الصلاة، باب الامر بتعهد القرآن، رقم : 789۔