The freed slave of the Messenger of Allah, Sayyiduna Abu Rafi’ (may Allah be pleased with him) says: Whenever the Messenger of Allah (peace and blessings be upon him and his family) heard the mu’adhdhin (caller to prayer), he would repeat what he said. When the mu’adhdhin reached“Hayya ‘ala-s-Salah, Hayya ‘ala-l-Falah,”the Messenger of Allah (peace and blessings be upon him and his family) would say:“La hawla wa la quwwata illa billah.”