1 Kings 6:15-16

¹⁵And he built the walls of the house within with boards of cedar; from the floor of the house unto the joists of the ceiling, he covered them on the inside with wood; and he covered the floor of the house with boards of cypress.

¹⁶And he built twenty cubits on the hinder part of the house with boards of cedar from the floor unto the joists; he even built them for himself within, for a Sanctuary, even for the most holy place.