2 Samuel (Author Compiled by Isaiah from records of Samuel, David, Nathan, and Gad.)
Chapter 24
10And 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.
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.