Musannaf Ibn Abi Shayba 33:124

Abu Khalid al-Ahmar narrated to us, from Ibn ‘Ajlan, from Zayd ibn Aslam, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Allah only admits into Paradise the one who hopes for it, and He only keeps away from the Fire the one who fears it. And Allah only shows mercy to the one who shows mercy."