Reference : Hisn al-Muslim 109

اللّهُـمَّ عالِـمَ الغَـيْبِ وَالشّـهادَةِ
فاطِـرَ السّماواتِ وَالأرْضِ
رَبَّ كـلِّ شَـيءٍ وَمَليـكَه
أَشْهَـدُ أَنْ لا إِلـهَ إِلاّ أَنْت
أَعـوذُ بِكَ مِن شَـرِّ نَفْسـي
وَمِن شَـرِّ الشَّيْـطانِ وَشِـرْكِه
وَأَنْ أَقْتَـرِفَ عَلـى نَفْسـي سوءاً
أَوْ أَجُـرَّهُ إِلـى مُسْـلِم
Allāhumma `ālima ‘l-ghaybi wash-shahādah, 
fātiras-samāwāti wa ‘l-ardh,
Rabba kulli shay'in wa malīkah, 
ash-hadu an lā ilāha illā ant,
a`ūdhu bika min sharri nafsī, 
wa min sharrish-shayṭāni wa shirkih, 
wa an aqtarifa `alā nafsī sū'an, 
aw ajurrahu ilā Muslim.


O Allah, Knower of the unseen and the evident, 
Maker of the heavens and the earth, 
Lord of everything and its Master, 
I bear witness that there is none worthy of worship but You. 
I seek refuge in You from the evil of my 
soul,
and from the evil of Satan and his helpers.
(I seek refuge in You) from bringing evil upon my soul
and from harming any Muslim.

Reference:
Abu Dawud 4/317. See also Al-Albani, SahihAt-Tirmidhi 3/142.

Chapter: Before sleeping