Lady Hafsa bint Umar (may Allah be pleased with them both) narrates that when the Noble Prophet (peace and blessings be upon him) intended to sleep, he would place his right hand under his cheek and recite this supplication: "Allahumma qini ‘adhabaka yawma tab’athu ‘ibadak." (O Allah, protect me from Your punishment on the Day You resurrect Your servants.) He would say these words three times, and the right hand of the Prophet (peace and blessings be upon him) was for eating and drinking, while the left hand was for other (some) necessities.