Assalam-o-Alaikum WR WBSahih BukhariVolume 9, Book 93, Number 490: Narrated Abu Huraira (radiallahu anho): The Prophet (salallahu alaihi wasallam) said, "When anyone of you goes to bed,he should dust it off
thrice with the edge of his garment, and say: BismikaRabbi wada'tu janbi, wa bika arfa'hu. In amsakta nafsi faghfir laha, wa inarsaltaha fahfazha bima tahfaz bihi 'ibadaka-s-salihin."