And David’s heart smote him after that he had numbered the people. And David said unto the LORD, I have sinned greatly in that I have done: and now, I beseech thee, O LORD, take away the iniquity of thy servant; for I have done very foolishly.
David felt really bad after counting all the people. He told God he had done something very wrong and asked Him to forgive his mistake because it was a very dumb thing to do.