"The Adhan during the time of Messenger of Allah, Abu Bakr, and Umar was when the Imam came out, [and when] the Iqamah was called for the Salat. Then Uthman [may Allah be pleased with him] added a third call at Az-Zawra."
كَانَ الأَذَانُ عَلَى عَهْدِ رَسُولِ اللَّهِ ﷺ وَأَبِي بَكْرٍ وَعُمَرَ إِذَا خَرَجَ الإِمَامُ وَإِذَا أُقِيمَتِ الصَّلاَةُ فَلَمَّا كَانَ عُثْمَانُ ؓ زَادَ النِّدَاءَ الثَّالِثَ عَلَى الزَّوْرَاءِ
In the lifetime of the Prophet, Abu Bakr and ʿUmar, the Adhan for the Jumua prayer used to be pronounced when the Imam sat on the pulpit. But during the Caliphate of ʿUthman when the Muslims increased in number, a third Adhan at Az-Zaura' was added. Abu ʿAbdullah said, "Az-Zaura' is a place in the market of Medina."
كَانَ النِّدَاءُ يَوْمَ الْجُمُعَةِ أَوَّلُهُ إِذَا جَلَسَ الإِمَامُ عَلَى الْمِنْبَرِ عَلَى عَهْدِ النَّبِيِّ ﷺ وَأَبِي بَكْرٍ وَعُمَرَ ؓ فَلَمَّا كَانَ عُثْمَانُ ؓ وَكَثُرَ النَّاسُ زَادَ النِّدَاءَ الثَّالِثَ عَلَى الزَّوْرَاءِ
[Machine] "That the call on Friday used to begin when the Imam sat down, and when the prayer was established during the time of the Messenger of Allah ﷺ and Abu Bakr and Umar, until the time of Uthman and when people increased, the third call was added to al-Zawra."
«أَنَّ النِّدَاءَ يَوْمَ الْجُمُعَةِ كَانَ أَوَّلُهُ إِذَا جَلَسَ الْإِمَامُ وَإِذَا قَامَتِ الصَّلَاةُ عَلَى عَهْدِ رَسُولِ اللهِ ﷺ وَأَبِي بَكْرٍ وَعُمَرَ ؓ حَتَّى إِذَا كَانَ عُثْمَانُ ؓ وَكَثُرَ النَّاسُ فَزَادَ النِّدَاءَ الثَّالِثَ عَلَى الزَّوْرَاءِ»