During the time of the Prophet Muhammad, ﷺ the practice was to have one adhan (call to prayer), along with the iqamah (announcement), before the Friday prayer. The sequence involved the mu’adhdhin giving the adhan, followed by the Prophet delivering the two khutbahs (sermons), and then the iqamah would be given to initiate the prayer.

As the population in Madinah increased during the caliphate of ‘Uthmaan ibn ‘Affaan, he introduced a third adhan. This additional adhan called the first adhan, was intended to notify people that it was Friday, prompting them to prepare for the prayer before the regular adhan given after the sun passed the meridian.

This practice initiated by ‘Uthmaan continued thereafter and has been followed by most Muslims across various regions and centuries. The adoption of the first adhan is attributed to ‘Uthmaan's ijtihad (independent reasoning) and his desire to improve things for the Muslim community. 

The acceptance of this practice is rooted in the fact that it aligns with the traditions of the Rightly Guided Caliphs, including ‘Uthmaan and ‘Ali, along with the companions present at that time. The continuity of this practice underscores its acceptance and endorsement within the broader Muslim community.

Hadith

Uthman bin 'Affan introduced the second (additional) Adhan on Fridays when the number of people in the mosque increased. Previously, the Adhan on Fridays used to be pronounced only after the Imam had taken his seat (on the pulpit). Sahih al-Bukhari