Musnad Ahmad 1:50

Bahz narrated to us, Shu'bah narrated to us, Ya'la ibn 'Ata informed me, he said: I heard 'Amr ibn 'Asim saying: I heard Abu Hurairah saying: Abu Bakr said: "O Messenger of Allah, teach me something to say when I reach the morning, and when I reach the evening, and when I take to my bed." He said: "Say: O Allah, Creator of the heavens and the earth, Knower of the unseen and the witnessed - or he said: O Allah, Knower of the unseen and the witnessed, Creator of the heavens and the earth - Lord of everything and its Sovereign, I bear witness that there is no god but You. I seek refuge in You from the evil of my soul, and the evil of the devil and his shirk (polytheism/traps)."