Ezekiel 40:17-19

17And he brought me into the outer court, and behold, there were cells, and a pavement made for the court round about: thirty cells were upon the pavement.

18And the pavement was by the side of the gates, answering to the length of the gates, [namely] the lower pavement.

19And he measured the breadth from the front of the lower gate unto the front of the inner court outside, a hundred cubits eastward and northward.