Isa bin Talhah (may Allah have mercy on him) said: We went in to Sayyiduna Mu'awiyah (may Allah be pleased with him). The mu'adhdhin gave the adhan and said: 'Allahu akbar, Allahu akbar' (Allah is the Greatest, Allah is the Greatest), and Sayyiduna Mu'awiyah (may Allah be pleased with him) said: "Allahu akbar, Allahu akbar." He said: 'Ashhadu an la ilaha illallah' (I bear witness that there is no god but Allah), and Sayyiduna Mu'awiyah (may Allah be pleased with him) said: "Ashhadu an la ilaha illallah." He said: 'Ashhadu anna Muhammadan rasulullah' (I bear witness that Muhammad is the Messenger of Allah), and Sayyiduna Mu'awiyah (may Allah be pleased with him) said: "And I too: Ashhadu anna Muhammadan rasulullah." Yahya said: A companion of ours narrated to us that when he said: 'Hayya 'ala al-salah' (Come to the prayer), he said: 'La hawla wa la quwwata illa billah' (There is no might and no power except with Allah), then he said: "This is how we heard it from your Prophet (peace and blessings be upon him)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1928