preach at (one)
To deliver a stern, moralistic lecture to one (about something). I wish you would stop preaching at me about my spending habits, Dad. The priest spends every Sunday preaching at us about the same old sins and vices.
preach at someone
to lecture or moralize at someone. Don't preach at me! I don't need any of your moralizing. I really don't wish to be preached at.