Musannaf Ibn Abi Shayba 21:180

Ibn Fudayl narrated to us, from ‘Ata’ ibn al-Sa’ib, from his father, who said: I was sitting with ‘Ammar, and a man came to him and said: "Shall I not teach you words?"—as if he were attributing them to the Prophet, may Allah bless him and grant him peace—"When you take to your bed at night, say: 'O Allah, I have submitted my soul to You, and I have entrusted my affair to You, and I have sought refuge for my back with You. I believe in Your Book which You revealed and Your Prophet whom You sent. O Allah, my soul, You created it for Yourself; its life is for You and its death is for You. So if You keep it, have mercy upon it, and if You let it remain, protect it with the protection of faith.'"