2 Samuel 24:10

And David's heart smote him, his conscience began to bother him, after that he had numbered the people, while the census was still being taken. And David, becoming conscious of the sinfulness of his act, said unto the Lord, I have sinned greatly in that I have done, the offense of his pride was directed against the Lord; and now, I beseech Thee, O Lord, take away the iniquity of Thy servant, the guilt which he had loaded upon himself by his transgression; for I have done very foolishly. It was a short penitential prayer, which he apparently sent up to God during a sleepless night.