Test the Spirit
According to Islamic history, Prophet Muhammad was said to practice meditation in a cave for fifteen years. Then in A.D. 610 he claimed "truth descended' on him while meditating in cave Hira. As one day Muhammad was in the cave, a spirit visited him, pressed his chest three times and asked him to read:
When it was the night on which God honoured him with his mission and showered mercy on His servants thereby, Gabriel brought him the command of God. "He came to me," said the apostle of God (i.e. Muhammad), while I was asleep, with a coverlet of brocade whereon was some writing, and said,
'Read' I said, what shall I read? He pressed me with it so tightly that I thought it was death; then he let me go and said,
'Read!' I said what I shall read?' he pressed me with it so that I thought it was death; then he let me go and said,
'Read!' I said what I shall read?' he pressed me with it for the third time so that I thought it was death and said,
'Read' l Said, what then shall l read and this l said only to deliver myself from him, lest he should do, the same to me again. He said; read in the name of lord who create, who created man of blood coagulated. Read 'thy lord is the most beneficent, who taught by the pen, taught that which they knew not unto men'. So l read it, and he departed from me. And awoke from my sleep, and it was as though these words were written on my heart,"
(Ibn Ishaq. The Life of Muhammad. (translated by A. Guillame) New York, OUP, 1980. p.81)
In other words, as Muhammad was one day meditating in the cave, a spirit visited him, pressed his chest tightly such that, he thought he was going to die. But on each occasion, Muhammad told the spirit he was illiterate and couldn't read.
After this encounter with the spirit in the cave, Muhammad thought he had been visited by a demon and ran to his wife in fear. He said to Khadija, his wife, 'cover me' she covered him until his fear was over. Muhammad related what had transpired in the cave to his wife and said, 'O Khadija, what is wrong with me? What has happened to me? I am afraid for myself! However, Khadija and on the advice of lbn Neafal her cousin managed to convince Muhammad that the spirit was Gabriel. But the spirit did not introduce itself as the angel Gabriel.