Hadith #598 (Sahih al-Bukhari)
Book: Call to Prayers (Adhaan)
Narrator(s): Isa bin Talha bin 'Ubaidullah عيسى بن طلحة بن عبيد الله
Grade: Sahih

that he had heard Muawiya repeating the words of Adhan up to “Wa ash-hadu anna Muhammadan rasulul-lah (and I testify that Muhammad is Allah’s Messenger (ﷺ).)”

Source: https://parallelquran.com/hadith/sahih-al-bukhari-598/