اللَّهُمَّ خَلَقْتَ نَفْسِي وَأَنْتَ تَوَفَّاهَا لَكَ مَمَاتُهَا وَمَحْيَاهَا ، إِنْ أَحْيَيْتَهَا فَاحْفَظْهَا ، وَإِنْ أَمَتَّهَا فَاغْفِرْ لَهَا ، اللَّهُمَّ إِنِّي أَسْأَلُكَ الْعَافِيَةَ
Translation 
O Allah, verily You have created my soul and You shall take it’s life, to You belong it’s life and it’s death. If You should keep my soul alive then protect it, and if You should take it’s life then forgive it. O Allah, I ask You to grant me well-being.
Transliteration
allaahumma khalaqta nafsee wa anta tawaffaahaa, laka mamaatuhaa wa maḥyaahaa, in aḥyaytahaa faḥfaẓhaa, wa in amattahaa faghfir lahaa, allaahumma innee as’alukal-‛aafiyah
Sources:
Muslim No# 2712
