Charles Ellicott Commentary Ezekiel 42:16

"He measured on the east side with the measuring reed five hundred reeds, with the measuring reed round about." — Ezekiel 42:16 (ASV)

With the measuring reed.— According to Ezekiel 40:5, the reed was six cubits long; 500 reeds—the measure of each side of the square—was therefore 3,000 cubits, or about 5,000 feet—nearly a mile. Of course, such a space, quite as large as was ever enclosed by the walls of ancient Jerusalem, would have been impossible upon the hill of Moriah, and various efforts have been made by some of the commentators to reduce the size; but the use of the reed as the unit of measurement is decisive.

The objection to the size is without value, as Keil well says, “for the simple reason that in Ezekiel 45 and 48 there follow still further statements concerning the separation of the sanctuary from the rest of the land, which are in perfect harmony with this, and show most indisputably that the Temple seen by Ezekiel was not to have its seat in the ancient Jerusalem;” nor, it may be added, in any other earthly locality. It is a vision not designed to have a material realisation.