Renowned compilers of authentic traditions of Islam agree on the following account of the first revelations received by the Prophet.
Muhammad would seclude himself in the cave of Mount Hira and worship three days and nights. He would, whenever he wished, return to his family at Mecca and then go back again, taking with him the necessities of life. Thus he continued to return to Khadijah from time to time until one day the revelation came down to him and the Angel Gabriel (Jibreel) appeared to him and said: "Read!" But as Muhammad was illiterate, having never received any instruction in reading or writing, he said to the angel: "I am not a reader." The angel took hold of him and squeezed him as much as he could bear, and then said again: "Read!" The Prophet said: "I am not a reader." The Angel again seized the Prophet and squeezed him and said: "Read! In the Name of your Lord, Who has created (all that exists), has created man from something that clings. Read! And your Lord is the Most Generous, Who has taught (the writing) by the pen, has taught man that which he knew not. Surah 96: 1-5