Musnad Ahmad 1018:111

'Abd al-Razzaq narrated to us, Ma'mar informed us, from al-Zuhri, from Abu Umamah ibn Sahl ibn Hunayf, from some of the companions of the Prophet, may God bless him and grant him peace, who said: The Prophet, may God bless him and grant him peace, said: "While I was sleeping, I saw the people being presented to me, and upon them were shirts. Some of them reached the chest, and some of them reached lower than that. Then Umar was presented to me, and upon him was a shirt that he was dragging." They said: "How did you interpret that, O Messenger of God?" He said: "The religion."