The Messenger of Allah ﷺ said, "While I was asleep, I saw people being presented to me, and they were wearing shirts. Some of the shirts reached the chest, and some fell short of that. Then Umar bin Khattab passed by me wearing a shirt that he was dragging behind him."They asked, "What did you interpret this to mean, Messenger of Allah?"He replied, "Religion."
قال رسول الله ﷺ: بينما أنا نائم رأيت الناس يعرضون علي وعليهم قمص، منها ما يبلغ الثدي، ومنها ما يبلغ دون ذلك، ومر علي عمر بن الخطاب، وعليه قميص يجره، قالوا: ما أولته يا رسول الله؟ قال: الدين.
Bukhari narrated it in the Book of Dream Interpretation (7008), and Muslim in the Book of the Virtues of the Companions (2390), both through the route of Yaqub bin Ibrahim, who said, my father narrated to me, from Salih, from Ibn Shihab, who said, Abu Umama bin Sahl narrated to me, that he heard Abu Saeed Khudri, and he related it.His saying, "wearing a shirt that he drags," contains an allusion to the Islamic conquests that would take place during his caliphate, and to the fact that their effects would remain for those who came after him. Ibn Hajar mentioned in Fath al-Bari (12/396) that the interpreters of dreams agreed that the shirt is interpreted as religion, and that its length indicates the lasting effects of its wearer after him.