Albert Barnes Commentary Ezekiel 42:20

"He measured it on the four sides: it had a wall round about, the length five hundred, and the breadth five hundred, to make a separation between that which was holy and that which was common." — Ezekiel 42:20 (ASV)

The “sanctuary” proper is probably here the most holy place as distinguished from the rest of the temple (Ezekiel 41:23; Ezekiel 45:3); but the term was capable of extension first to the whole temple, then to all the ground that was separated to “holy” as distinguished from “profane,” that is, common uses.

In the vision the courts rose on successive platforms, the outer court being raised seven steps above the precincts, the inner court eight steps above the outer, and the temple itself ten steps above the court of sacrifice.