Albert Barnes Commentary 2 Chronicles 3:5

"And the greater house he ceiled with fir-wood, which he overlaid with fine gold, and wrought thereon palm-trees and chains." — 2 Chronicles 3:5 (ASV)

The greater house - That is, the holy place, or main chamber of the temple, located between the porch and the Most Holy Place (as in 2 Chronicles 3:7).

He paneled it with fir wood - This means he covered or lined it. This does not refer to the ceiling, which was entirely made of wood, but to the walls and floor, which were stone with a covering of planks. In this context, the word translated “fir” probably does not have the narrow meaning found in 2 Chronicles 2:8, where it is contrasted with cedar, but rather a broader meaning that includes cedar.

Palm trees and chains - See 1 Kings 6:29. The “chains” are thought to be garlands or festoons.