Ezekiel 43:12-13

12This is the law of the temple: All its surrounding territory on top of the mountain will be especially holy. Yes, this is the law of the temple.

13“These are the measurements of the altar in units of length (each unit being the standard length plus three inches): The gutter is 21 inches deep and 21 inches wide, with a rim of nine inches around its edge. This is the base of the altar.