He prepared, i.e. adorned and fitted it for the receipt of the ark.
In the house, Heb. in the middle of the house, or building; not the middle mathematically or exactly, but in general within the house, as that phrase, in the middle, oft signifies; as Deu_4:11Jos_7:21Dan_3:26.
Within, or, in the uttermost part of the house; for so this was, the entrance into the house being at the other end.