לְאַרְבַּ֨ע רוּח֜וֹת מְדָד֗וֹ ח֤וֹמָה לוֹ֙ סָבִ֣יב ׀ סָבִ֔יב אֹ֚רֶךְ חֲמֵ֣שׁ מֵא֔וֹת וְרֹ֖חַב חֲמֵ֣שׁ מֵא֑וֹת לְהַבְדִּ֕יל בֵּ֥ין הַקֹּ֖דֶשׁ לְחֹֽל׃
他在四面量了那地方；四周有牆圍繞，長五百，寬五百，用來分隔聖地和俗地。
English Explanation of Mishnah Middot
The Temple Mount was five hundred cubits by five hundred cubits. This accords with the dimensions stated in Ezekiel 42:20.
Rashi
And with this measurement [lit. from this measurement.] With the measuring rod by which the 500 by 500 square of the Temple Mount was measured, as is stated above (42:20): “To four sides he measured it; its wall all around, five hundred rods, etc.”