Musnad Ahmad 30:843

Muhammad ibn Ja‘far narrated to us, Shu‘bah narrated to us, from Ya‘la ibn ‘Ata’, he said: I heard ‘Amr ibn ‘Asim narrating that he heard Abu Hurayrah narrating from the Prophet, peace and blessings of Allah be upon him: That Abu Bakr said to the Prophet, peace and blessings of Allah be upon him: "Inform me of something I may say when I reach the morning and when I reach the evening." He said: "Say: O Allah, Knower of the unseen and the witnessed, Originator 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 from the evil of Satan and his shirk (polytheism/entrapment). Say it when you reach the morning, when you reach the evening, and when you take to your bed."