John Wesley on Ezekiel 40:17

The outward court - So called in regard of the more inward court, between that where he was, and the temple itself; this court, was the second about the temple. Chambers - Not only lodging rooms for the priests, but also store - houses for tithes and offerings. A pavement - A beautiful floor laid with checker works. The whole floor of this court was thus paved. Thirty chambers - That is, fifteen on the south side of the gate, and fifteen on the north side, built over the pavement.