Hadith No. 2 From An-Nawawis Forty Hadith
Also on the Authority of `Umar , who said:
One day while we were sitting with the Messenger of Allah there appeared before us a man whose clothes were exceedingly white and whose hair was exceedingly black; no signs of journey were to be seen on him and none of us knew him. He walked up and sat down by the Prophet .
Resting his hands against his and placing the palms of his hands on his thighs he said: O Muhammad, tell me about Islaam. The Messenger of Allah said: Islaam is to testify that there is no deity worthy of worship but Allah and Muhammad is the Messenger of Allah, to perform prayers, to make zakaah, to fast in Ramadaan, and to make the pilgrimage to the House if you were able to do so.
He said: You have spoken rightly; and we were amazed at him asking him and saying that he had spoken rightly. He said: Tell me about eeman. He said: It is to believe in Allah, His angels, His books, His messengers, and the Last Day, and to believe in divine destiny, both the good and the evil thereof. He said: You have spoken rightly.
He said: Then tell me about ihsaan. He said: It is to worship Allah as though you are seeing Him and while you see Him not, yet truly He sees you.
He said: Then tell me about the Hour. He said: The one questioned about it knows no better than the questioner. He said: Then tell me about its signs. He said: that the slave-girl will give birth to her mistress and that you will see barefooted, naked destitute herdsmen competing in constructing lofty buildings.
Then he took himself off and I stayed for a time. The he said: O `Umar, do you know who the questioner was? I said: Allah and His Messenger know best. He said: It was Gabriel, who came to teach you your religion.
It was related by Muslim.