…what He sends down—they say, “You are nothing but a fabricator.” Yet most of them do not know. Say: “The Holy Spirit has brought it down from your Lord in truth.” (Q 16:101–102)

In both Ṣaḥīḥ collections it is related from ʿĀʾishah that al-Ḥārith ibn Hishām asked the Messenger of Allah—may Allah bless him and grant him peace—“How does revelation come to you?” He replied:

“Sometimes it comes to me like the reverberating sound of a bell; that is the hardest for me to bear. When it departs I have retained whatever it conveyed. At other times the angel appears to me in the form of a man, speaks to me, and I grasp what he says.”

ʿĀʾishah added: “I have seen him when revelation was descending upon him on an intensely cold day; when it left him, sweat would be dripping from his forehead.”

She also reported—in the two Ṣaḥīḥs:

“The first form in which revelation began for the Messenger of Allah, may Allah bless him and grant him peace, was the righteous dream during sleep: he would see no dream except that it came as clear as the break of dawn. Then seclusion was made dear to him. He used to withdraw to the Cave of Ḥirāʾ, devoting himself there to taḥannuth (acts of worship) for several nights at a time before returning to his family for provisions, after which he would go back again. He continued in this until the Truth came to him while he was in the cave. The angel appeared and said, ‘Read!’ He replied, ‘I am not one who can read.’ The angel took hold of me and pressed me so hard that I was exhausted, then released me and said, ‘Read!’ I said, ‘I am not one who can read.’ He pressed me a second time until I could bear no more, then released me and said, ‘Read!’ I again said, ‘I am not one who can read.’ He pressed me a third time until I was at my limit, then released me and said:

Recite in the name of your Lord who created,
created man from a clinging clot.
Recite! Your Lord is the Most Generous,
who taught by the pen,
taught man what he did not know. (Q 96:1-5)

She then narrated the rest of the account at length, mentioning the interval when revelation ceased. In his rendition of that period, Jābir reported that the Prophet, peace and blessings be upon him, said:

“While I was walking I suddenly heard a voice from the sky. I looked up, and there was the angel who had come to me at Ḥirāʾ, seated upon a chair between heaven and earth. I was struck with awe and returned home, saying, ‘Cover me up!’”