One day, while we were sitting with the Messenger of Allah ﷺ, a man appeared before us with strikingly white clothes and strikingly black hair.He then mentioned a long hadith in which it was said,The man asked, "Tell me about the Hour."The Messenger of Allah ﷺ replied, "The one being asked about it knows no more than the questioner."The man said, "Then tell me about its signs."He answered, "That a slave girl will give birth to her mistress, and that you will see barefoot, naked, destitute shepherds of sheep competing in constructing tall buildings."Umar continued, Then the man departed, and I waited for a while.Then the Messenger of Allah ﷺ said to me, "Umar, do you know who the questioner was?"I replied, "Allah and His Messenger know best."He said, "That was Jibreel, who came to teach you your religion."
بينما نحن عند رسول الله ﷺ ذات يوم إذ طلع علينا رجل شديد بياض التياب شديد سواد الشعر،… فذكر حديثا طويلا وجاء فيه قال: فأخبرني عن الساعة، قال: ما المسئول عنها بأعلم من السائل قال: فأخبرني عن أماراتها، قال: أن تلد الأمة ربتها، وأن ترى الحفاة العراة العالة رعاء الشاء يتطاولون في البنيان. قال: ثم انطلق فلبثت مليا، ثم قال لي: يا عمر! أتدري من السائل؟ قلت: الله ورسوله أعلم. قال: فإنه جبريل أتاكم يعلمكم دينكم.
Reported by Muslim in the Book of Faith (8:1), via Kahmas, from Abdullah bin Burayda, from Yahya bin Yamar, from Abdullah bin Umar, from his father Umar bin Khattab, who related it in a long hadith.