How the Qur'an Was Revealed and Compiled
Section 15 of 28 · Foundations of Islam · Hamza Yusuf
A People Who Memorised
After thirteen years, the Qurʾān is basically being memorised. Among oral peoples, people who really still maintain these traditions — in the West African oral tradition, for instance — there are peoples who will recite epic poems of tribes; and if they do not recite them exactly as they learned them, then they literally lose their job. They cannot be a storyteller. So the Arabs were people who memorised poetry and related poetry exactly as they had received it. They had phenomenal memories. The Mauritanians in West Africa have memories that are extraordinary; the amount of information retained exactly is phenomenal.
For people who do not understand this oral tradition, it is very hard to imagine that a human being can memorise this entire text, the Arabic text, and not make a mistake. Yet one who has memorised it can be brought in, and the Qurʾān read to him with a verse purposely left out, and he will correct it immediately.
The other thing that is interesting about the Qurʾān is that people who memorise it, and even parts of it, will quickly learn that the Qurʾān is a self-correcting book, because it has a very unusual rhythm; so that if a verse moves out of sync, suddenly one is aware: I have said something wrong.
There is the account of a man who led the ṣubḥ prayer, reading a rather long sūrah, and at the end of it said a verse that is actually out of the Qurʾān, but was not the verse that went in that place, and used almost the same words. And that morning, for probably the next half hour, something was bothering him; and then he realised what it was — he had said the verse wrong. And he corrected himself. Nobody corrected him in the prayer, but he corrected himself.
It is very interesting when one memorises the Qurʾān. Many have tried to memorise a lot of things — poetry at prep school, a piece of Shakespeare, and things like that. The really interesting thing about the Qurʾān is, first, that it is facilitated. It is very easy to memorise. It is not hard to memorise for many, many people. And the other thing is that it is actually quite difficult to forget, if it is recited within reasonable time limits and repeated every once in a while. It is very difficult to forget.