يَقُولُ مِثْلَ مَا يَقُولُ المُؤَذِّنُ إِلاَّ فِي ((حَيَّ عَلَى الصَّلَاةِ وَحَيَّ عَلَى الْفَلَاحِ)) فَيقُولُ: ((لاَ حَوْلَ وَلاَ قُوَّةَ إِلاَّ بِاللَّهِ)).
'One repeats just as the mu-aththin (one who calls to prayer) says, except when he says: Hayya AAalas-salah (or) hayya AAalal-falah - 'come to prayer, come to success' - instead, one should say: 'La hawla wala quwwata illa billah' - 'There is no might nor power except with Allah.'
Al-Bukhari 1/152, Muslim 1/288.