preach to (one)
1. To deliver a sermon to one. The priest loved preaching to his congregation and sharing the word of God with them.
2. To deliver a firm moralistic lecture or discourse to one (about something). I wish you would stop preaching to me about my spending habits, Dad. The politician preached to his supporters of the need for new healthcare legislation.
preach to someone
to give a moral discourse to someone. Please don't preach to me. I know that I did wrong. When you preach to us like that, we don't pay any attention to you.