Sahih Bukhari | Volume 9 | Hadith Number 490

Narrated by Abu Huraira
The Prophet said, "When anyone of you goes to bed, he should dust it off thrice with the edge of his garment, and say: Bismika Rabbi wada'tu janbi, wa bika arfa'hu. In amsakta nafsi faghfir laha, wa in arsaltaha fahfazha bima tahfaz bihi 'ibadaka-s-salihin."