Musannaf Ibn Abi Shayba 2:33

Abu Bakr narrated to us, he said: Ghundar narrated to us, from Shu'bah, he said: 'Abd al-Rahman ibn 'Abis narrated to us, he said: I heard Abu Mahdhurah saying regarding the end of his Adhan that his Adhan was double [phrasing] and his Iqamah was single [phrasing], and the conclusion of his Adhan was: "Allah is the Greatest, Allah is the Greatest, there is no god but Allah." Abu Bakr narrated to us, he said: Jarir narrated to us, from 'Abd al-'Aziz ibn Rufay', from Abu Mahdhurah, the like of it. Abu Bakr narrated to us, he said: 'Abd al-Wahid ibn Sulayman narrated to us, from 'Ubayd Allah ibn 'Umar, from Nafi', from Ibn 'Umar, that he used to make the end of his Adhan: "Allah is the Greatest, Allah is the Greatest, there is no god but Allah." Abu Bakr narrated to us, he said: Ghundar informed us, from Shu'bah, he said: 'Abd al-Rahman ibn 'Abis informed us, he said: I heard Abu Mahdhurah saying at the end of his Adhan: "Allah is the Greatest, Allah is the Greatest, there is no god but Allah."