Sahih Bukhari Volume 5, Book 57, Hadith Number 40.

Narated By Abu Said Al-Khudri : I heard Allah’s Apostle saying, “While I was sleeping, the people were presented to me (in a dream). They were wearing shirts, some of which were merely covering their (chests). and some were a bit longer. ‘Umar was presented before me and his shirt was so long that he was dragging it.” They asked, “How have you interpreted it, O Allah’s Apostle?” He said, “Religion.”