Silsilah as-Sahihah 3107 — Supplications and etiquette before sleeping

Sayyiduna Bara bin Azib (may Allah be pleased with him) says that when the Messenger of Allah (peace and blessings be upon him) would sleep, he would place his hand under his right cheek and recite this supplication: "O Allah! On the day You raise Your servants, save me from Your punishment." This hadith is also narrated from Sayyiduna Hudhayfah bin al-Yaman (may Allah be pleased with him) and Sayyidah Hafsah bint Umar (may Allah be pleased with her).