2 Corinthians 10:9-12

I do not want to appear to be frightening you with my letters. For they say, “His letters are weighty and strong, but his bodily presence is weak, and his speech of no account.” Let such a person understand that what we say by letter when absent, we do when present. Not that we dare to classify or compare ourselves with some of those who are commending themselves. But when they measure themselves by one another and compare themselves with one another, they are without understanding.