Musannaf Ibn Abi Shaybah 28237 — Those who said: When you lie down

Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) said that when the Prophet (peace and blessings be upon him) intended to sleep, he would recite this supplication: "O Allah, protect me from Your punishment on the day You gather Your servants." And he (peace and blessings be upon him) would place his right hand under his cheek.