Praise be to Allah.
The First Revelation: "Read in the Name of Your Lord"
It is reported in Sahih Al-Bukhari and Sahih Muslim from `Urwah ibn Az-Zubayr that `Aishah the wife of the Prophet (peace and blessings of Allah be upon him) said:
“The beginning of the Revelation that came to the Messenger of Allah (peace and blessings of Allah be upon him) was good dreams; he never saw a dream but it came true like bright daylight. Then seclusion was made dear to him, and he used to go to the cave of Hira’ and worship there, which means that he went and devoted himself to worship for a number of nights before coming back to his family to collect more provisions, then he would go back again. Then he would go back to Khadijah to collect more provisions. (This went on) until the truth came to him suddenly when he was in the cave of Hira’. The angel came and said, `Read!’ The Messenger of Allah (peace and blessings of Allah be upon him) said, `I am not a reader.’ He said, Then he took hold of me and squeezed me until I could not bear it any more. then he released me and said, `Read!’ I said, `I am not a reader.’ He took hold of me and squeezed me a second time until I could not bear it any more, then he released me and said, `Read!’ I said, `I am not a reader.’ He took hold of me and squeezed me a third time until I could not bear it any more, then he released me and said,
{Read! In the Name of your Lord Who has created (all that exists). He has created man from a clot (a piece of thick coagulated blood). Read! And your Lord is the Most Generous. Who has taught (the writing) by the pen. He has taught man that which he knew not.} [Al-`Alaq 96:1-5 – interpretation of the meaning]
Khadijah’s Support and Visit to Waraqah ibn Nawfal
Then the Messenger of Allah (peace and blessings of Allah be upon him) went back with his heart beating wildly, until he came to Khadijah (may Allah be pleased with her) and said, `Cover me! Cover me!’ They covered him till his fear went away. Then he said to Khadijah, `O Khadijah, I fear for myself,’ and he told her what had happened. Khadijah said, `Nay, be of good cheer, for by Allah, Allah will never disgrace you. You uphold the ties of kinship, speak truthfully, help the poor and destitute, serve your guests generously and assist those who are stricken by calamity.’
Then Khadijah took him to Waraqah ibn Nawfal, the son of her paternal uncle. He was a man who had become a Christian during the Jahiliyyah (i.e., the pre-Islamic era). He used to write Arabic script and he used to write from the Gospel in Arabic as much as Allah willed he should write. He was an old man who had become blind. Khadijah said, `O son of my uncle, listen to what your nephew says.’ Waraqah said: `O son of my brother, what have you seen?’ [The Prophet (peace and blessings of Allah be upon him)] told him what he had seen. Waraqah said: `This is the Namus [Jibril] who came down to Moosa. Would that I were young and could live until the time when your people will drive you out.’
The Messenger of Allah (peace and blessings of Allah be upon him) said, `Will they really drive me out?’ Waraqah said, `Yes. Never has there come a man with that which you have brought, but he was persecuted. If I should live to see that day, I will support you strongly.’ But a few days later, Waraqah died, and the Revelation also ceased for a while, until the Messenger of Allah (peace and blessings of Allah be upon him) was filled with grief.
The Revelation Resumes with Surah Al-Muddathir
Muhammad ibn Shihab said: Abu Salamah ibn `Abd Ar-Rahman told me that Jabir ibn `Abdullah Al-Ansari said: “The Messenger of Allah (peace and blessings of Allah be upon him) said, speaking of that period when the revelation ceased: `Whilst I was walking, I heard a voice from the sky. I looked up and saw the angel who had come to me in Hira’, sitting on a chair between the heavens and the earth. I felt scared of him, so I came home and said, “Cover me, cover me [with blankets]!” So they did, then Allah revealed the words:
{O you (Muhammad) enveloped in garments! Arise and warn! And magnify your Lord (Allah)!
And purify your garments! And keep away from Ar-Rujz (the idols)!} [Al-Muddathir 74:1-5– interpretation of the meaning].’”
Abu Salamah said: Al-Rujz were the idols which the people of the Jahiliyyah used to worship. Then the revelation came frequently after that. (Narrated by Al-Bukhari, 4572 and Muslim, 231)
For more details, please refer to the following answers: 205660, 180883, 209069, 156077, 135586, 315345, 5142, 427817
And Allah knows best.
