Hadith 1464

Hudhaifah (May Allah be pleased with him) reported: Whenever the Messenger of Allah (PBUH) intended to go to sleep, he would place his right hand under his (right) cheek and supplicate: "Allahumma qini 'adhabaka yauma tab'athu 'ibadaka (O Allah! Guard me against Your punishment on the Day when You will resurrect Your slaves)."

[At-Tirmidhi].

In a narration in Abu Dawud, Hafsah (May Allah be pleased with her) said: Before going to sleep the Messenger of Allah (PBUH) would recite this Du'a three times.