´As-Sa'ib bin Yazid said:` "The third Adhan was ordered by 'Uthman when the number of people in Al-Madinah increased. The Messenger of Allah (ﷺ) only had one Adhan, and the Adhan on Friday was when the Imam sat down."
Hadith ReferenceSunan an-Nasa'i / The Book of Jumu\'ah (Friday Prayer) / Hadith: 1394