Is what the man mentioned in the mosque did on Friday—saying to people, "Pray upon the Prophet and you will find a place," and repeatedly reciting verses of the Qur'an aloud during the sermon—considered contrary to the Sunnah, and does silence regarding this reprehensible act make the silent one a mute devil?

The statement of this man to someone who could not find a place: "Pray upon the Prophet (peace be upon him) and you will find a place," involves a detailed explanation: If he intended that praying upon the Prophet might facilitate that, then there is no harm, due to the general virtue of it in relieving worries and forgiving sins. However, this is not exclusive to it, as one might pray and not achieve their desire. But if he intended that the Prophet himself provides the place, then this is polytheism (shirk) and misguidance. As for him raising his voice by repeating verses during thew sermon, it is a disturbance and ostentation, and he should be advised gently and kindly outside of the sermon time.