Musnad Ahmad 658:208

'Ali ibn Hafs narrated to us, Sufyan narrated to us, from Abu Ishaq, from al-Bara' who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "When you go to your bed, say: O Allah, I have submitted my soul to You, and I have turned my face toward You, and I have entrusted my affair to You, and I have leaned my back upon You, out of desire and fear of You. There is no refuge and no escape except to You. I have believed in Your Book which You revealed, and in Your Prophet whom You sent. For if you die during your night, you will die upon the natural disposition (fitrah), and if you wake up, you will attain good."