Mukhtasar Bukhari

Narrated from Sayyiduna Muawiyah bin Sufyan (may Allah be pleased with him) that he was sitting on the pulpit when the muezzin gave the call to prayer. When he said (Allahu Akbar Allahu Akbar), Muawiyah (may Allah be pleased with him) also said (Allahu Akbar Allahu Akbar). Then the muezzin said ((Ashhadu an la ilaha illallah)), so Muawiyah (may Allah be pleased with him) said ((Wa ana)). The muezzin said ((Ashhadu anna Muhammadur Rasulullah)), so Muawiyah (may Allah be pleased with him) said ((Wa ana)). When the call to prayer was finished, Muawiyah (may Allah be pleased with him) said: O people! I heard the Messenger of Allah (peace and blessings of Allah be upon him) at this very place (i.e., the pulpit) that when the muezzin gave the call to prayer, he (peace be upon him) would say just as you have heard me say.