Exodus 26:33

The sanctuary, &c. That part of the tabernacle, which was without the veil, into which the priests daily entered, is here called the sanctuary, or holy place; that part which was within the veil, into which no one but the high priest ever went in, and he but once a year, is called the holy of holies, (literally, the sanctuaries of the sanctuary,) as being the most holy of all holy places. (Challoner) --- It occupied only one-third of the tabernacle. (Menochius)