Musannaf Ibn Abi Shayba 17:1223

Ibn Numayr narrated to us, he said: Ubayd Allah ibn [Umar] narrated to us, from Sa’id ibn Abi Sa’id al-Maqburi, from Abu Hurayrah, that the Messenger of Allah (may Allah bless him and grant him peace) said: "When one of you intends to lie down on his bed, let him take the inner part of his lower garment and dust his bed with it, for he does not know what has come upon it after him. Then let him lie on his right side, then let him say: 'In Your name, my Lord, I have placed my side, and by You I lift it. So if You withhold my soul, have mercy on it, and if You send it back, protect it with that which You protect Your righteous servants.'"