Musnad Ahmad 31:613

Sayyar narrated to us, Ja'far narrated to us, al-Mu'alla ibn Ziyad narrated to us, al-'Ala' ibn Bashir al-Muzani narrated to us—and he was, by Allah, as far as I knew, brave when meeting [the enemy] and a weeper when [Allah was] mentioned—from Abu al-Siddiq al-Naji, from Abu Sa'id al-Khudri, who said: I was in a circle of the Ansar, and some of us were covering others due to nakedness, and a reciter among us was reciting to us, and we were listening to the Book of Allah. Suddenly, the Messenger of Allah (peace and blessings of Allah be upon him) stood over us and sat among us, to count himself with them. The reciter stopped, so he said: "What were you saying?" We said: "O Messenger of Allah, a reciter of ours was reciting the Book of Allah to us." The Messenger of Allah (peace and blessings of Allah be upon him) gestured with his hand and formed a circle with it, signaling to them to form a circle. So the circle turned. I did not see the Messenger of Allah (peace and blessings of Allah be upon him) recognize anyone among them except me. He said: "Rejoice, O company of the poor, you will enter Paradise before the rich by half a day, and that is five hundred years."