رَضِيتُ بِاللَّهِ رَبًّا وَبِالْإِسْلَامِ دِينًا وَبِمُحَمَّدٍ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ نَبِيًّا
Transliteration
Raditu billahi Rabban wa bil-islami dinan wa bi-Muhammadin sallallahu 'alayhi wa sallama nabiyya
English meaning
I am pleased with Allah as my Lord, with Islam as my religion, and with Muhammad (PBUH) as my Prophet.
When is it recited?
Recited 3 times in the morning and evening.
Its virtue
Whoever says this will be granted intercession on the Day of Judgment.
Source
Abu Dawud, Adab 101, 5072; Tirmidhi, Da'awat 13, 3389