Hadith from Imam Nawawi's 40 hadiths
Ḥadīth No. 2
Also on the authority of `Umar, who said: [One day] while we were sitting with the Messenger of Allah (), a man came over to us whose clothes were exceedingly white and whose hair was exceedingly black; no signs of travel were seen on him, but none of us knew him. He came and sat down opposite the Prophet (pbuh) and rested his knees against his, placing the palms of his hands on his thighs. He said, "O Muḥammad , inform me about Islam." The Messenger of Allah (pbuh) said, "Islam is to testify that there is no god but Allah and that Muḥammad is the Messenger of Allah, to establish prayer, to give zakāh, to fast Ramadhān, and to make the pilgrimage to the House if you are able to do so." He said, "You have spoken the truth," and we wondered at his asking him and confirming it. He said, "Then inform me about īmān." He said, "It is to believe in Allah, His angels, His books, His messengers, and the Last Day, and to believe in predestination, both the good and the evil thereof." He said, "You have spoken the truth." He said, "Then inform me about iḥsān." He said, "It is to worship Allah as though you see Him; if you do not see Him, indeed, He sees you." He said, "Then inform me about the Hour." He said, "The one questioned about it knows no more than the questioner." He said, "Then inform me of its signs." He said, "That the slave-woman will give birth to her mistress and that you will see barefooted, naked, destitute shepherds competing in the loftiness of constructions." Then he departed, and I stayed for a time. Then he said, "O `Umar, do you know who the questioner was?" I said, "Allah and His Messenger are more knowing." He said, "It was Gabriel. He came to you to teach you your religion." (Narrated by Muslim)