Musnad Ahmad ibn Hanbal: Book 2, Hadith 269

It was narrated from Ibn ʼUmar, from `Umar, that the Prophet (ﷺ) said: ʼUmar bin al-Khattab (رضي الله عنه) told me: Whilst we were with the Messenger of Allah (ﷺ) one day, a man came to us whose garment was exceedingly white and whose hair was exceedingly black, and we did not see any signs of travel on him, and none of us knew who he was. He came and sat before the Prophet (ﷺ), resting his knees against his and placing his hands on his thighs. He said: O Muhammad, tell me about Islam: what is Islam? The Messenger of Allah (ﷺ) said: `Islam means to bear witness that there is no god except Allah and that Muhammad is the Messenger of Allah (ﷺ), to establish regular prayer, to pay zakali, to fast Ramadan and to perform pilgrimage to the House (the Ka`bah), if you have the means.` He said: You have spoken the truth. He (‘Umar) said: It amazed us, how he questioned him and said that he had spoken the truth. He said: Tell me about faith (Eeman). He said: `Faith is to believe in Allah, His angels, His Books, His Messengers, the Last Day, and to believe in al-qadar (the divine will and decree), both good and bad.` He said: You have spoken the truth. He said: Tell me about ihsan: what is ilisan? – Yazeed said: – `It is to worship Allah as if you can see Him, for although you cannot see Ilim, He sees you.` He said: Tell me about the Hour. He said: “The one who is asked about it does not know more than the one who is asking.” He said: Then tell me about its signs. Ise said: `When the slave woman gives birth to her mistress, and when you see the barefoot, naked, destitute shepherds competing in the construction of lofty buildings.” He said: Then he went away. He sumar waited for a while – Yazeed said: three (days). Then he (the Prophet (ﷺ) said to me: `O`Umar, do you know who that questioner was?` I said: Allah and His Messenger know best. He said: “That was Jibreel, who came to you to teach you your religion.`

Ibn ‘Umar said. `Umar (رضي الله عنه) told us: We were sitting with the Messenger of Allah (ﷺ) and he mentioned the same hadeeth, except that he said: No signs of travel were to be seen on him. And he- said: `Umar said: 1 waited for three (days), then the Messenger of Allah (ﷺ) said: “oʻUmar…”