أَعُوذُ بِاللَّهِ الْعَظِيمِ وَبِوَجْهِهِ الْكَرِيمِ وَسُلْطَانِهِ الْقَدِيمِ مِنَ الشَّيْطَانِ الرَّجِيمِ. بِسْمِ اللَّهِ وَالصَّلَاةُ وَالسَّلَامُ عَلَى رَسُولِ اللَّهِ، اللَّهُمَّ افْتَحْ لِي أَبْوَابَ رَحْمَتِكَ
Transliteration
A'udhu billahil-'azimi wa biwajhihil-karimi wa sultanihil-qadimi minash-shaytanir-rajim. Bismillahi was-salatu was-salamu 'ala rasulillahi, Allahummaftah li abwaba rahmatik
English meaning
I seek refuge in Almighty Allah, by His noble face and His primordial authority, from the accursed Satan. In the name of Allah, and prayers and peace be upon the Messenger of Allah. O Allah, open the gates of Your mercy for me.
When is it recited?
Recited when entering the mosque with the right foot.
Source
Abu Dawud, Salat 18, 465; Ibn Majah, Masajid 2, 771