Authentic Supplication Number 028.

If one of you gets up from his bed and then returns to it, then let him shake it out [yanfudh ((48)) it] with the inside of his waist wrapper three times, for one does not know what succeeded him on it, and when he has lied down he should say Bismika rabbee wadha`tu jambee, wabika 'arfa`uhu, fa 'in 'amsakta nafsee farhamha, wa 'in 'arsaltaha, fahfathha bima tahfathu bihi `ibadaka 'as-saliheena (49).

Then upon waking up let him say: Al-hamdu lil-lahi 'allathee `afanee fee jasadee, wa radda `alayya roohee, wa 'athina lee bithikrihi (50).

Footnotes.
(48) Yanfudh is a form of the verb nafadha which is a perturbation with the purpose of removing something. For example this same word is used to refer to perturbations such as shaking-out a dust mat. In this case you are using the inner side of your garment (izar) and perturbing the surface of your bed as if you were dusting it off.

(49) In Thy name, O my Lord, I have laid my side, and by You I shall lift it, if You keep hold of my soul [i.e. take my life] then have mercy on it, and if You are to send it on, then preserve it in [or with] that which You preserve your pious bondservants in [or with].

(50) All praise be to Allah that has sparred me in my body, returned my soul upon me, and has permitted that I engage in his remembrance.

Reporters.
Reported by At-Tirmithi who said it was comely. Al-Albani said it was of good ascription, and he included it in The Authentic of Good Sayings as #28.