Additional Azan on Friday
The additional azan [call to prayer] that is called on Fridays began in the time of Hazrat Uthman (ra). Details regarding this is as follows.
Zuhri has narrated from Saib bin Yazid who stated that during the time of the Holy Prophet (sa), Hazrat Abu Bakr (ra) and Hazrat Umar (ra), the first azan for Jumuah would be called when the imam sat down on the minbar [pulpit]. In the time of Hazrat Uthman (ra), when the Muslim population increased significantly, he ordered for a third azan to be called from Zaura. Abu Abdillah states that Zaura was a place in the market of Medina.
(Sahih al-Bukhari, Kitab al-Jumuah, Bab al-Adhan Yaum al-Jumuah, Hadith 912)
This incident has also been mentioned in Fiqh-e-Ahmadiyya in relation to this hadith that in the time of the Holy Prophet (sa), Hazrat Abu Bakr (ra) and Hazrat Umar (ra), only one azan was called on Fridays from near the minbar – which was always placed inside the mosque. Later, in the time of Hazrat Uthman (ra), the second azan was initiated which was called from a rock named Zaura situated near to the door of the mosque.
(Fiqh-e-Ahmadiyya [Ibadat] p. 122)
In Ni‘mat-ul-Bari, a commentary of Sahih Bukhari, under this hadith, it is written: “Ibn Shihab Zuhri narrates from Saib that the mention of the third azan in this chapter is including the Iqamat [call before the prayer begins].”
(Ni‘mat al-Bari fi Sharh Sahih al-Bukhari, Vol. 2, p. 837, Hadith 912, Rumi Publications Lahore, 2013)
There were two azans previously and a third one was added later. In the narration I read earlier, it was stated owing to the increase in the Muslim population, a third azan was called at Zaura. The third azan was as such that the first and second azan would be called, then the takbir [for iqamah] has also been referred to using the word azan. Thus, in this way people were called to prayer three times.