Commentary on the Bible, by Adam Clarke, , at sacred-texts.com
This chapter gives us a description of the priests' chambers and their use, with the dimensions of the holy mount on which the temple stood, vv. 1-20.
He brought me forth into the utter court - He brought him out from the temple into the court of the priests. This, in reference to the temple, was called the outer court; but the court of the people was beyond this.
A walk of ten cubits' breadth inward - This seems to have been a sort of parapet.
They shall lay their garments wherein they minister - The priests were not permitted to wear their roles in the outer court. These vestments were to be used only when they ministered; and when they had done, they were to deposit them in one of the chambers mentioned in the thirteenth verse.
He measured the east - north - south - west side - Each of which was five hundred reeds: and, as the building was square, the area must have been nearly thirteen thousand paces. No wonder this was called a city. See Eze 40:2.
It had a wall round about - to make a separation between the sanctuary and the profane place - The holy place was that which was consecrated to the Lord; into which no heathen, nor stranger, nor any in a state of impurity, might enter. The profane place was that in which men, women, Gentiles, pure or impure might be admitted. Josephus says War, lib. vi., c. 14, that in his time there was a wall built before the entrance three cubits high, on which there were posts fixed at certain distances, with inscriptions on them in Latin and Greek, containing the laws which enjoined purity on those that entered; and forbidding all strangers to enter, on pain of death. See Calmet.