(Imam Bukhari narrates that) Muhammad bin Ubaidullah narrated to us, he said: Ibrahim bin Sa'd narrated to us, from Salih, from Ibn Shihab, from Abu Umamah bin Sahl, this hadith, that Hazrat Abu Sa'id Al-Khudri (may Allāh be pleased with him) used to say that the Messenger of Allāh ﷺ said:

While I was sleeping, I saw (in a dream) that people were being presented before me, and all of them were wearing shirts; some of their shirts reached to the chest, and some were shorter than that. And Umar bin Al-Khattab was presented before me, and he had such a shirt that he was dragging it (i.e., it was very long). The Companions asked: O Messenger of Allāh! What interpretation have you given to this? He said: Religion.