Sa’ib ibn Yazid narrated, “In the times of the Prophet Abu Bakr (RA) and Umar (RA) the adhan (for Friday salah) was called when the imam came out Then the iqamah was called. Then when Uthman (RA) came, he added a third call from the top of az-Zawra (a wall in the markets of Madinah from which the mu’adhdhin called).
[Ahmed 15228, Bukhari 912, Abu Dawud 1088, Nisai 1391, Ibn e Majah 1135]
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