Hisnul Muslim 23

Upon hearing the athan

وَأَنَا أَشْـهَدُ أَنْ لَا إِلـهَ إِلاَّ اللّهُ وَحْـدَهُ لَا شَـرِيكَ لَـهُ وَأَنَّ محَمَّـداً عَبْـدُهُ وَرَسُـولُهُ، رَضِيـتُ بِاللّهِ رَبَّاً، وَبِمُحَمَّـدٍ رَسُـولاً، وَبِالإِسْلَامِ دِينـاً

Wa 'anaa 'ash-hadu 'an laa 'ilaaha 'illallaahu wahdahu laa shareeka lahu wa 'anna Muhammadan 'abduhu wa Rasooluhu, radheetu billaahi Rabban, wa bi-Muhammadin Rasoolan wa bil'islaami deenan.

After the muazzin says the words of affirmation of Faith (Shahadah) says: "I bear witness that none has the right to be worshiped but Allah alone, Who has no partner, and that Muhammad is His slave and His Messenger. I am pleased with Allah as my Lord, with Muhammad as my Messenger and with Islam as my religion".