Is it permissible for the adhan to be called inside the mosque on Friday, and is it authentically reported that this was done during the time of the Messenger of Allah (peace be upon him) or the Companions?

Al-Tabarani narrated from Al-Sa'ib bin Yazid that the Prophet (peace be upon him) had one muezzin who would call the Adhan at the mosque's entrance on Friday when he sat on the minbar, and when he descended, he would call the Iqamah for prayer. Abu Bakr and Umar also followed this practice. When Uthman's caliphate came and the population increased, he ordered a first Adhan to be called in the marketplace from a house of his called Az-Zawra' to alert the people. This indicates that the Adhan is for notification and that Uthman introduced the second Adhan.

The Adhan should not be called inside the mosque without a loudspeaker. A group of scholars have held that doing so is an innovation that negates the benefit of the Adhan in making people outside the mosque hear it, as those already inside the mosque do not need it. It is assumed that the Adhan should be called from the usual place of Adhan to make those not in the mosque hear it, as was the practice during the time of the Prophet (peace be upon him) and the caliphs. However, in these times, loudspeakers make it unnecessary to go outside the mosques, so there is no harm in calling the Adhan inside them, as the purpose has been achieved. For those who do not have loudspeakers, it is better for them to do what the Prophet (peace be upon him) and the Rightly Guided Caliphs used to do.