Ezekiel 43:12-13

This is the law of the house: its entire area on the top of the mountain all around shall be most holy. Behold, this is the law of the house. “And these are the measurements of the altar by cubits (the cubit being a cubit and a handbreadth): the base shall be a cubit and the width a cubit, and its border on its edge round about one span; and this shall be the height of the base of the altar.