a good example is the best sermon

proverb One's actions or behavior can teach more effectively than a lecture. Children will learn good behavior much more efficiently if they see it practiced regularly by their parents. A good example is the best sermon, after all. I guess a good example really is the best sermon, because everyone is talking about how the politician cycles to work each day and drinks out of reusable water bottles. It's becoming downright trendy. Ray's always eaten a very healthy diet, just like his dad. It's true what they say—a good example is the best sermon.