Musnad Abu Ya'la al-Mawsili 42:199

Abu Khaythama narrated to us, Jarir narrated to us, from al-A'mash, from Abu Salih, from Abu Sa'id al-Khudri, who said: The Prophet (peace be upon him) said: "Paradise and the Fire argued. The Fire said: 'In me are the tyrants and the arrogant.' And Paradise said: 'In me are the weak people and the poor among them.' He said: So He judged between them: 'You, Paradise, are My mercy; I show mercy through you to whom I will. And you, Fire, are My punishment; I punish through you whom I will. And for both of you is the filling of it.'"