Charles Ellicott Commentary 2 Chronicles 9:8

"Blessed be Jehovah thy God, who delighted in thee, to set thee on his throne, to be king for Jehovah thy God: because thy God loved Israel, to establish them for ever, therefore made he thee king over them, to do justice and righteousness." — 2 Chronicles 9:8 (ASV)

On his throne —that is, Jehovah’s throne (Compare to 1 Chronicles 28:5). Kings has, on the throne of Israel.

To be king for the Lord your God. —A further insistence on the idea that Solomon was but the vicegerent of Jehovah. The clause is added by the chronicler, but need not be called “an evidently wilful alteration” (Thenius).

To establish. —This phrase is missing in the Hebrew of Kings, but is probably original, as the Septuagint there has it.