Musnad Ahmad 435:69

Yahya narrated to us, from Muhammad ibn ‘Amr, who said: My father narrated to me, from my grandfather, who said: We were with Mu‘awiyah, and the caller to prayer (mu’adhdhin) said: "Allah is the Greatest, Allah is the Greatest." Mu‘awiyah said: "Allah is the Greatest, Allah is the Greatest." He said: "I bear witness that there is no god but Allah." He said: "I bear witness that there is no god but Allah." He said: "I bear witness that Muhammad is the Messenger of Allah." He said: "I bear witness that Muhammad is the Messenger of Allah." He said: "Come to prayer." He said: "There is no power and no strength except by Allah." He said: "Come to success." He said: "There is no power and no strength except by Allah." He said: "Allah is the Greatest, Allah is the Greatest." He said: "Allah is the Greatest, Allah is the Greatest." He said: "There is no god but Allah." He said: "There is no god but Allah." He said: "This is how the Messenger of Allah (may Allah bless him and grant him peace)—or your Prophet—used to say when the caller to prayer called."