Assalamu aleikum,
Will start a new thread since this topic has got involved in another topic, and it is given a better highlight and place on its own.
Part 1.
Memorisation and oral transmission
The Prophet Muhammad, saws himself was the first to commit a revelation to memory after the Angel Gabriel had brought it to him:
'Move not thy tongue concerning the (Qur'an) to make haste therewith. It is for Us to collect it and promulgate it; but when We have promulgated it, follow thou its
recital' (75: 16-19).
'... an apostle from God, rehearsing scriptures, kept pure and holy ...'
(98: 2).
Memorisation by the Companions
The Prophet, saws then declared the revelation and instructed his Companions to memorise it. When (Ibn Mas'ud) arrived at the maqAm, he read
"In the name of God the Compassionate the Merciful, The Compassionate who taught the Qur'an ..."
(55:1)
The Prophet, saws encourages Memorisation
'Narrated 'Uthman bin 'Affan: The Prophet said: "The most superior among you (Muslims) are those who learn the Qur'an and teach it".' Bukhari, VI, No. 546.
It is also well known that the recital of the Qur'an during the daily prayers is required and hence many Companions heard repeatedly passages from the revelation, memorised them and used them in prayer.
The Prophet, saws sent Teachers
The Prophet, saws sent teachers to communities in other places so that they might receive instruction in Islam and the Qur'an.
Qur'an Readers among the Companions
'Narrated Qatada: I asked Anas bin Malik: Who collected the Qur'an at the time of the Prophet? He replied, Four, all of whom were from the Ansar: Ubay bin Ka'b, Mu'adh bin Jabal, Zaid bin Thabit and Aba Zaid.' Bukhari, VI, No. 525.
The Qur'an Memorised in the Prophet's Lifetime
It is therefore certain that the Qur'an had been memorised by the Companions of the Prophet, saws during his lifetime. This tradition continued among the Companions after the Prophet's death and, later, among the tabi'un and all generations of Muslims that have followed, until today.
To be continued...