Musannaf Ibn Abi Shayba 33:339

Abu Mu'awiyah narrated to us, from al-A'mash, from Khaythama, who said: Abdullah said: "By the One besides whom there is no god, no believing servant has been given anything better than having a good opinion of Allah. By the One besides whom there is no god, no believing servant has a good opinion of Allah except that He gives him that, for all goodness is in His hand."