Musnad Ahmad 1:80

Hashim ibn al-Qasim narrated to us, Shayban narrated to us, from Layth, from Mujahid, who said: Abu Bakr al-Siddiq said: The Messenger of Allah, peace and blessings of Allah be upon him, commanded me to say when I reach the morning, when I reach the evening, and when I take to my bed at night: "O Allah, Creator of the heavens and the earth, Knower of the unseen and the witnessed, You are the Lord of everything and its Sovereign. I bear witness that there is no god but You alone, You have no partner, and that Muhammad is Your servant and Your Messenger. I seek refuge in You from the evil of my soul, and from the evil of Satan and his shirk (polytheism/traps), and that I commit evil against my soul, or draw it to a Muslim."