According to the explanation of the above-mentioned writers, the prophet referred to his own pure soul as the "Faithful Spirit" or the giver of revelation. The Qur'an, however, does not support this view and names Gabriel as the deliverer of the verses.
God says in chapter II:97, "Say (O Muhammad, to mankind): Who is an enemy to Gabriel! for it is he who has revealed (this book) to your heart by God's permission." This verse refers to Jews who wanted to know who had revealed the Qur'an to the Prophet. He replied that it was Gabriel. They said, "We are enemies of Gabriel as he it was who gave us (the tribe of Israel) the laws and legal punishments and as we are enemies to him, we do not believe in the book which he has brought. " Thus God replies to them in the verse that Gabriel revealed the Qur'an to the Prophet by God's permission. God further says that the Qur'an is to be believed in, and that it is not the speech of Gabriel. It is important to note that the Qur'an, in the words of the above verse was revealed "to the heart" of the Prophet Muhammad by Gabriel.
In another verse [XXVI:193-4] we read that it was transmitted by the Faithful Spirit, "which the Faithful Spirit has brought down upon your heart". By comparison of these two verses it becomes evident that it is the angel Gabriel who is meant here by the words, "Faithful Spirit".
In chapter LXXXI:1923 God describes the transmittance of revelation: That this is in truth the word of an honoured messenger (Gabriel), Mighty established in the presence of the Lord of the Throne, one to be obeyed and trustworthy and your comrade (the Prophet) is not mad. Surely he saw him on the clear horizon.
These verses show that Gabriel was one of the intimates of God, possessing great power and trust. Again in chapter XL:7 we read, "Those who bear the power, and all who are around Him, praise their Lord and believe in Him and ask forgiveness for those who believe." Such characteristics as belief in God and seeking forgiveness from him are only to be expected from independent, sentient creatures.
In chapter IV:172-173 we read,

The Messiah will never disdain to be a servant of God, nor will the favoured angels. Whoever disdains His service and is proud, He will gather them all to Himself, then as for those who believe and do good, He will pay them fully their rewards and give them more out of His grace, and as for those who disdain and are proud, He will punish them with a painful doom. And they will not find for themselves besides Allah a guardian or a helper.

It is clear that although the Messiah, Jesus, and the favoured angels do not disobey the commands of God they are, nevertheless, warned of a painful punishment on the day of reckoning if they were to commit a wrong. The possibility of neglect of their duties or committing wrong action is neces- sarily dependent on their being sentient beings, possessed of free will and entrusted with the task of transmitting the revelation of God. Thus we learn from the Qur'an that Gabriel is the Faithful Soul: he is trustworthy and to be obeyed because he is obeyed by angels in his task. An indication of these obedient angels comes in the verse,

But truly it is a warning-so let whoever will pay heed to it, on honoured leaves exalted, purified (set down by scribes) noble and righteous