Musnad Abu Ya'la al-Mawsili 159:42

Bishr narrated to us, Abd al-Rahman narrated to us, from his father, from al-A'raj, from Abu Hurayrah, who said: I heard the Messenger of Allah (peace and blessings of Allah be upon him) say: "Paradise and Hell disputed. Hell said: 'I have been favored with the arrogant and the tyrants.' Paradise said: 'Why is it that none enter me except the weak people, the lowly, and the helpless?' Allah said to Paradise: 'You are only My mercy; I show mercy through you to whom I will.' And He said to Hell: 'You are only My punishment; I punish through you whom I will. And for each one of you is its filling.'"