Charles Ellicott Commentary 1 Chronicles 21:7

"And God was displeased with this thing; therefore he smote Israel." — 1 Chronicles 21:7 (ASV)

And God was displeased. This verse also is not found in Samuel, which instead has, And David’s heart smote him after that he had numbered the people. The peculiarities of expression in Samuel suggest textual corruption.

The chronicler’s verse is a sort of general heading, or anticipative summary, to the following narrative. The margin rightly renders the first clause (see Genesis 21:0 for the same unusual construction).