Reference : Hisn al-Muslim 55

اللّهُـمَّ إِنِّـي أَعـوذُ بِكَ مِـنْ عَذابِ القَـبْر،
وَمِـنْ عَذابِ جَهَـنَّم، 
وَمِـنْ فِتْـنَةِ المَحْـيا وَالمَمـات، 
وَمِـنْ شَـرِّ فِتْـنَةِ المَسيحِ الدَّجّال
Allāhumma ‘innī ‘a`ūdhu bika min `adhābi ‘l-qabri, 
wa min `adhābi jahannam, 
wa min fitnati ‘l-maḥyā wa ‘l-mamāti, 
wa min sharri fitnati ‘l-masīḥid-dajjāl.


O Allah, I seek refuge in You from the punishment of the grave, and from the punishment of Hell-fire, and from the trials of life and death, and 
from the evil of the trial of the False Messiah.

Reference:
Al-Bukhari 2/102, Muslim 1/412, and this is Muslim's wording.

Chapter: After the last tashahhud and before salam