1 Kings 6:15-16

15He paneled the walls of the House on the inside with cedar planks of cedar; from the floor of the House to the ceiling he overlaid on the inside with wood; and he overlaid the floor of the House with planks of cypress.

16Then he partitioned off 20 cubits at the rear part of the House, using cedar boards from the floor to the ceiling, building it as the inner Sanctuary—the Holy of Holies.