Ezekiel 42:19-20

Thomson(i) 19 then turning at the south he measured five hundred with his measuring reed. 20 The four sides of the height and breadth of this same reed. And he appointed this, namely, the surrounding parapet wall which was five hundred cubits on the east side and five hundred cubits broad to make a separation between the Holies and the vacant space before the wall, which was to be comprehended in the plot of the house.