For expelling the devil and his whisperings1 du'a
Seeking refuge with Allah against him (i. e. by saying I seek refuge in Allah from Satan the outcast...
أَعُوذُ بِاللَّهِ مِنَ الشَّيطَانِ الرَّجِيمِ
"Seeking refuge with Allah against him (i. e. by saying I seek refuge in Allah from Satan the outcast)."