The Messenger of Allah (ﷺ) said: “When one of you becomes frightened during sleep, then let him say:

أَعُوْذُ بِكَلِمَاتِ اللَّهِ التَّامَّةِ (التَّامَّاتِ) مِنْ غَضَبِهِ وَعِقَابِهِ وَ(مِنْ) شَرِّ عِبَادِهِ وَمِنْ هَمَزَاتِ الشَّيَاطِيْنِ وَأَنْ يَحْضُرُوْنِ

A'oodhu bikalimaatil-laahit-taammaati min ghadhabihi wa 'iqaabihi, wa (min) sharri 'ibaadihi, wa min hamazaatish-shayaateeni wa 'an yahduroon

I seek refuge in the Perfect Words of Allah from His anger and His punishment, from the evil of His slaves and from the taunts of devils and from their presence.

Reference: Hasan (Albani). Tirmidhi: 3528