From Sahih Bukhari (Hadith 613):
Narrated Yahya as above (586) and added:"Some of my companions told me that Hisham had said, "When the Mu'adh-dhin said, "Haiyi `alassala (come for the prayer)." Muawiya said, "La hawla wala quwata illa billah (There is neither might nor any power except with Allah)" and added, "We heard your Prophet saying the same
Reference: Bukhari 613