Is Friday Prayer valid if the Imam ascends the pulpit and there are only three worshippers in the mosque, then the mosque fills during the khutbah?

Scholars have differed regarding the stipulation of a specific number for the Friday sermon, and there is no explicit text concerning this. As long as the mosque is full during the sermon, then the Friday prayer is valid at that time, because the presence of the required number is not stipulated from the very beginning of the sermon. Rather, it is sufficient to hear the obligatory parts of it (praising Allah, sending blessings upon the Prophet, reciting a verse, and enjoining piety towards Allah).