Musnad Abu Ya'la al-Mawsili 117:250

Zuhayr narrated to us, Affan narrated to us, Hammad narrated to us, Thabit narrated to us, he said: I heard Anas saying regarding the Prophet (may Allah bless him and grant him peace), he said: "There shall remain of Paradise what Allah wills to remain, then Allah shall create for it a creation from what He wills."