Whenever the Messenger of Allāh صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ wanted to sleep, he would place his [right] hand beneath his [right] cheek and say:
اللَّهُمَّ قِنِي عَذَابَكَ يَوْمَ تَبْعَثُ عِبَادَكَ
“O’ Allāh save me from Your Punishment on the Day when you shall raise your servants.”
Silsilah as-Saheehah, 2754 | Shaykh al-Albāni رحمه الله