Musannaf Ibn Abi Shaybah 2142 — How the adhan and iqamah are performed

Ibn Abi Mahdhurah narrates that Sayyiduna Abu Mahdhurah (may Allah be pleased with him) used to say the words of the adhan once each in a low voice. Then, when he reached Ashhadu anna Muhammadan rasulullah (I bear witness that Muhammad is the Messenger of Allah), Ashhadu anna Muhammadan rasulullah, he would go back to Ashhadu an la ilaha illallah (I bear witness that there is no god but Allah) and say these words twice each, raising his voice. Then, when he reached Hayya 'ala al-salah (Come to the prayer), he would say Al-salatu khayrun min al-nawm (Prayer is better than sleep) in the first adhan of Fajr.