On Friday, Prophet Aadam alaihis salaam was created, admitted into Paradise and sent down to earth. The end of the world will be on a Friday. (Ibn Kathir)
Allah had appointed Friday as the day of congregation and festivity for people, but the previous nations did not appoint it as their sacred day. Before Islam, Friday was known as Yaumul Arubah. The first Arab to change the name to Yaumul Jumuah was Ka’b Ibn Luayy, 560 years before Prophet Muhammad sallallahu alaihi wa sallam. The Quraish used to gather on this day and Ka’b delivered a sermon. Ka’b was among the forefathers of the Prophet sallallahu alaihi wa sallam and stayed away from idol worship, believing in One Allah. Thus the importance of Friday was recognised in Arabia before Islam. (Mazhari)
Some narrations state that the Ansar of Madinah used to gather and pray, before Hijrah, on Friday before Jumuah prayer became obligatory.
From the time of the Prophet sallallahu alaihi wa sallam till the era of Umar radhiallahu anhu there was only one Athaan for Jumuah at the time of the Khutba in front of the Imam. The Muslim population grew rapidly in the era of Uthman radhiallahu anhu and this Athaan could not be heard by the large Muslim population on the outskirts of Madinah. He therefore initiated another Athaan which was called in the trading area further from the Musjid at his house in az-Zaurah, which could be heard throughout Madinah. No Sahaabi objected to this.
Ma’ariful Qur’aan Vol 8 Pg 453-4 English