When was Muhammad visited by Gabriel?

Answer 1

It was in the month of Ramadan when an incident took place, which would change the rest of Muhammad's life and the course of human history. Muhammad was forty years old and until now he had lived a relatively normal life. Until this day, he wasn't well known for anything apart from his honesty and good character. According to tradition, when Muhammad was nearly 40, he had been prone to spending long hours in retirement meditating and speculating over the aspects of creation around him; this meditative temperament was said to have helped to widen the mental gap between him and his compatriots. He would provide himself with simple food and water, and then head directly for the hills and ravines in the neighborhood of Meccah. One of these in particular was his favorite resort - a cave named Hira, in the Mount An-Nur. Only 2 miles from Mecca, it was a small cave 4 yards long and 1.75 yards wide.

"And the book is delivered to him that is not learned, saying, Read this, I pray thee: and he saith, I am not learned." [Isaiah, 29:12]

One day Muhammad was sitting alone in a cave in mount Hira, on the outskirts of Meccah when suddenly a man in white dress appeared to him. Muhammad himself described: "Then he took me and squeezed me vehemently and then let me go and repeated the order 'Recite.' 'I cannot recite' said I, and once again he squeezed me and let me till I was exhausted. Then he said, 'Recite.' I said, 'I cannot recite.' He squeezed me for a third time and then let me go and said:

"Read: In the name of thy Lord Who createth. Createth man from a clot. Read: And thy Lord is the Most Bounteous, Who teacheth by the pen, Teacheth man that which he knew not." [Qur'an: 96:1-5]

Answer 2

In many places and occasions including Hiraa cave in Mecca (or Makkah) and in Medina (or Madinah).