Charles Ellicott Commentary 2 Chronicles 9:25

"And Solomon had four thousand stalls for horses and chariots, and twelve thousand horsemen, that he bestowed in the chariot cities, and with the king at Jerusalem." — 2 Chronicles 9:25 (ASV)

And Solomon had four thousand stalls for horses and chariots, and twelve thousand horsemen. —See 1 Kings 4:26 (where the number of stalls is erroneously stated at 40,000).

The remainder of the verse coincides with 1 Kings 10:26.

Having already given an account of Solomon’s chariots and horses, and his importation of the latter from Egypt, in 2 Chronicles 1:14–17, an account which is identical with 1 Kings 10:26–29, the chronicler naturally avoids mere repetition of that passage in 2 Chronicles 9:25–28.