Jamieson, Fausset and Brown on 2 Samuel 24:17

17. David ... said--or, "had said,"

I have sinned ... but these sheep, what have they done?--The guilt of numbering the people lay exclusively with David. But in the body politic as well as natural, when the head suffers, all the members suffer along with it; and, besides, although David's sin was the immediate cause, the great increase of national offenses at this time had (2Sa 24:1) kindled the anger of the Lord.