Musnad Ahmad 31:112

Hassan and Rawh narrated to us, they said: Hammad ibn Salamah narrated to us, from ‘Ata’ ibn al-Sa’ib, from ‘Ubayd Allah ibn ‘Abd Allah ibn ‘Utbah, from Abu Sa’id al-Khudri, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Paradise and the Fire boasted to one another. The Fire said: 'O Lord, the tyrants, the arrogant, the kings, and the nobles enter me.' And Paradise said: 'O Lord, the weak, the poor, and the destitute enter me.' So Allah, Blessed and Exalted is He, said to the Fire: 'You are My punishment; I afflict with you whom I will.' And He said to Paradise: 'You are My mercy; you encompass everything, and for each of you is your fill.' Then its people are cast into the Fire, and it says: 'Is there any more?' He said: 'And they are cast into it, and it says: "Is there any more?" And they are cast into it, and it says: "Is there any more?" until He, Blessed and Exalted is He, comes to it and places His Foot upon it, so it draws together, and it says: "Enough, enough."' As for Paradise, its people remain in it for as long as Allah wills to remain, and Allah creates for it a creation as He wills."