While entering the masjid
أَعُوْذُ بِاللهِ الْعَظِيْمِ، وَبِوَجْهِهِ الْكَرِيْمِ، وَسُلْطَانِهِ الْقَدِيْمِ، مِنَ الشَّيْطَانِ الرَّجِيْمِ بِسْمِ اللهِ، وَالصَّلٰوةُ وَالسَّلَامُ عَلٰى رَسُولِ اللهِ اللّٰهُمَّ افْتَحْ لِيْ أَبْوَابَ رَحْمَتِكَ
I seek refuge in Almighty Allah, by His Noble Face, by His primordial power, from Satan the outcast. [In the Name of Allah, and blessings] [And prayers and peace be upon the Messenger of Allāh] O Allah, open before me the doors of Your mercy.
References
[Sunan Abu Dawud - 465-466]