IN THE DAYS OF THE NOBLE PROPHET (sallallahu alayhi wasallam)
Since the Noble Qur'aan was not revealed all at once, on the contrary, different verses of it were being revealed as and when appropriate, therefore, it was not possible from the very beginning to write and preserve it in a book form. So, during the initial stage of Islaam, major emphasis was laid on memory as a means of preserving the Noble Qur'aan.
When wahee (revelation) used to come in the very beginning, the Prophet (sallallahu alayhi wasallam) would tend to repeat its words instantly so that they would be memorized well enough. Thereupon, Allah Almighty directed him through the verses of Soorah Qiyaamah that he need not repeat words in a hurry immediately as revelation came. Allah Almighty would himself endow him with a memory that he will be unable to forget the words of the wahee once its descent has been completed. So it was that the moment the Qur'aanic verses would come to him, they would be committed to his memory the next moment. Thus, the blessed chest of the Prophet (sallallahu alayhi wasallam), was the most protected vault of the Noble Qur'aan, in which there was no chance of even some common mistake, editing or alteration.
Moreover, as a matter of additional precaution, he used to recite the Qur'aan before angel Jibra'eel alayhis salaam every year during the month of Ramadhaan; and the year he left this mortal world he completed a cumulative review of Qur'aanic recitation twice with Jibra'eel alayhis salaam.
