Hadith: The example of the companion of the Qur'an is like the owner of hobbled camels

عن ابن عمر رضي الله عنهما أن رسول الله صلى الله عليه وسلم قال: «إنّما مَثَلُ صَاحبِ الْقُرْآنِ كَمَثَلِ الإِبِلِ المُعَقَّلَةِ، إنْ عَاهَدَ عَلَيْهَا أمْسَكَهَا، وَإنْ أطْلَقَهَا ذَهَبَتْ».
[صحيح] - [متفق عليه]

Ibn ‘Umar (may Allah be pleased with him) reported: The Prophet (may Allah's peace and blessings be upon him) said: "The example of a companion of the Qur'an is like an owner of hobbled camels. If he vigilantly keeps them tied, he will retain them, but if he releases them, they will run away."
Sahih/Authentic. - [Al-Bukhari and Muslim]

Explanation

A companion of the Qur'an is someone who memorizes it and recites it from memory and hobbled camels are those that are tied with ropes. The commonality here is that if a camel owner keeps his camels tied up and is cautious and attentive to them, they will stay in his possession, but if he unties them and releases them, they will run away. Similarly, a person who knows the Qur’an by heart will continue to retain it in his memory if he takes care of it by consistent recitation and revision. However, if he does not do so, he will forget it and will only be able to recover it back by going through hardships and difficulties. In other words, the memorization of the Qur’an will continue in your memory if you continue to revise it and be attentive to it, in the same way that the camels will remain in their places if they are tied firmly. The parable of camels is given here because they are the domesticated animals that run away most, and it is hard to retrieve them back if they run away.