And Satan stood up against Israel and provoked David to number Israel. From the parallel passage, 2 Samuel 24:1, we learn that this was due to the fact that the Lord at this time withdrew His grace from David, and permitted the Tempter to prevail over him.
Related Commentaries of 1 Chronicles 21:1
1 Chronicles 21:1
1 And Satan stood up against Israel, and provoked David to number Israel.