A sermon is an oration or lecture by a preacher (who is usually a member of clergy). Sermons address a scriptural, theological, religious, or moral topic, usually expounding on a type of belief, law, or behavior within both past and present contexts. Elements of the sermon often include exposition, exhortation, and practical application.
Sermon of Jum'ah was always given by the Prophet Muhammad (SAWA) before the two Rak'ats of Jum'ah Prayer.
Mo'awiyah and Uthman before him tried changing it.
In the well known Sunni book Morooj Al-Thahab مروج الذهب (2:72) that Mo'awiyah prayed Jum'ah prayer on Wednesday when he returned from Siffeen.
Ahlul Bayt (AS) recorded and ordered their followers to record the knowledge. All supplications and sermons and Hadiths were written.
Ameerul Momineen was writing the knowledge from the Prophet in a book called Al-Jami’ah الجامعة.
All our Infallible Imams used to write and order their followers to write.