وَلِلَّهِ الْأَسْمَاءُ الْحُسْنَى فَادْعُوهُ بِهَا
Transliteration
Wa lillahil-asma'ul-husna fad'uhu biha
English meaning
And to Allah belong the most beautiful names, so call upon Him by them.
When is it recited?
Before any supplication.
Source
Al-A'raf 7/180