Choose your words carefully if you preach to the people back home. Those who knew you will remember things that make many messages seem odd. Prophetic moralizing, for example, would sound hypocritical coming from most folks in such circumstances.
In my case, P. T. Reppert would likely be out there in the congregation. P. T. once got an ugly black eye from a baseball bat I’d flung in anger across a playground. That pretty well knocks out the Sermon on the Mount as a possible text.