Sa’ib ibn Yazid narrated, “In the times of the Prophet ﷺ 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] --------------------------------------------------------------------------------