صحيح البخاري

Narrated Jabir bin 'Abdullah Al-Ansari (while talking about the period of pause in revelation) reporting the speech of the Prophet: "While I was walking, all of a sudden I heard a voice from the sky. I looked up and saw the same angel who had visited me at the cave of Hira' sitting on a chair between the sky and the earth. I got afraid of him and came back home and said, 'Wrap me (in blankets).' And then Allah revealed the following Holy Verses (of Quran): 'O you (i.e. Muhammad)! wrapped up in garments!' Arise and warn (the people against Allah's Punishment),... up to 'and desert the idols.' (74.1-5) After this the revelation started coming strongly, frequently and regularly."