Oral transmission of the revelation was based on hifz or memorization and the Prophet Muhammad 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)

The Prophet then declared the revelation and instructed his Companions to memorise it. The case of Ibn Mas'ud, who was the first man to publicly recite the Qur'an in Makka, shows that even in the very early phase of the Islamic umma recital of the revelation from memory was practised by the Companions:

'... the first man to speak the Qur'an loudly in Makka after the apostle was 'Abdullah bin Mas'ud. The Prophet's Companions came together and mentioned that the Quraish had never heard the Qur'an distinctly read to them ... When (Ibn Mas'ud) arrived at the maqam, he read "In the name of God the Compassionate the Merciful", raising his voice as he did so. "The Compassionate who taught the Qur'an ..." () ... They got up and began to hit him in the face; but he continued to read so far as God willed that he should read ... [Guillaume, E.: The Life of Muhammad (abbr. as Ibn Hisham), London, 55, pp. 141-2; Ibn Hisham: Sira al-nabi, Cairo, n.d., 1, p.206.] It is also reported that Abu Bakr used to recite the Qur'an publicly in front of his house in Makka. [Sira Ibn Hisham, The Life of Muhammad]