Sahih Bukhari Volume 9, Book 91, Hadith 7011

حَدَّثَنَا سَعِيدُ بْنُ عُفَيْرٍ، حَدَّثَنِي اللَّيْثُ، حَدَّثَنِي عُقَيْلٌ، عَنِ ابْنِ شِهَابٍ، أَخْبَرَنِي أَبُو أُمَامَةَ بْنُ سَهْلٍ، عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ ـ رضى الله عنه ـ قَالَ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ ‏"‏ بَيْنَا أَنَا نَائِمٌ رَأَيْتُ النَّاسَ عُرِضُوا عَلَىَّ، وَعَلَيْهِمْ قُمُصٌ، فَمِنْهَا مَا يَبْلُغُ الثَّدْىَ، وَمِنْهَا مَا يَبْلُغُ دُونَ ذَلِكَ، وَعُرِضَ عَلَىَّ عُمَرُ بْنُ الْخَطَّابِ وَعَلَيْهِ قَمِيصٌ يَجْتَرُّهُ ‏"‏‏.‏ قَالُوا فَمَا أَوَّلْتَهُ يَا رَسُولَ اللَّهِ قَالَ ‏"‏ الدِّينَ ‏"‏‏

Narrated By Abu Sa'id Al-Khudri : I heard Allah's Apostle saying, "While I was sleeping, I saw (in a dream) the people being displayed before me, wearing shirts, some of which (were so short that it) reached as far as their breasts and some reached below that. Then 'Umar bin Al-Khattab was shown to me and he was wearing a shirt which he was dragging (behind him)." They asked. What have you interpreted (about the dream)? O Allah's Apostle?" He said, "The religion."