Umar stated that one day when he and some other companions were with God's Messenger, a man with very white clothing and very black hair came up. Sitting down beside the Holy Prophet leaning his knees against his, and placing his hands on his thighs he said, "Tell me Muhammad about Islam."
The Holy Prophet said, " Islam means that you should testify that there is no god but Allah; that Muhammad is God's Messenger; that you should observe the prayer, pay the Zakat, fast during Ramadan, and make the pilgrimage to the House of God, if you have the means".
The visitor said "You have spoken the truth. Now tell me about faith "
The Holy Prophet said, "It means that you should believe in Allah, His angels, His books, His Apostles, and the last day, and that you should believe in the decreeing both of good and evil."
The man said that that was true. He then asked, "Now tell me about doing good."
The Holy Prophet said, "It means that you should worship Allah as if you are seeing Him, and if you aye not seeing him (percieve) that He is in fact seeing you."
The man accepted the statement as correct. He next asked, "Now tell me about the Hour".
The Holy Prophet said, "The one who is asked about is no better informed than the one who is asking".
Thereupon the man said, "Then tell me about its signs".
The Holy Prophet replied, "The signs are that a maid servant should beget her mistress, and that you should see barefooted naked poor men and shepherds exulting themselves in buildings."
The visitor felt satisfied then he sought leave to depart and as soon as leave was given he disappeared Umar who was present wondered who was the visitor.
Turning to Umar, the Holy Prophet said, "Do you know who was the visitor?"
Umar replied that he did not know.
Thereupon the Holy Prophet said, "He was Gabriel, who came to you to teach your religion."