Malik bin Dinar narrates: I climbed up to Ibn Abi Mahdhurah on top of al-Masjid al-Haram after he had given the adhan, and I said to him: "Tell me about the adhan your father used to give for the Messenger of Allah (peace and blessings be upon him)." He said: "He would begin with the takbir (first), and say: 'Ashhadu an la ilaha illallah, ashhadu anna Muhammadan rasulullah, hayya 'ala al-salah, hayya 'ala al-salah,' once each, then he would go back and say: 'Ashhadu an la ilaha illallah, ashhadu an la ilaha illallah, ashhadu anna Muhammadan rasulullah, ashhadu anna Muhammadan rasulullah,' until he reached the end of the adhan: 'Allahu akbar, Allahu akbar, la ilaha illallah.'"
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6706