Albert Barnes Commentary Ezekiel 43:12

"This is the law of the house: upon the top of the mountain the whole limit thereof round about shall be most holy. Behold, this is the law of the house." — Ezekiel 43:12 (ASV)

See also Ezekiel 47:12. This is the law of the ordinance of the new sanctuary. After the consecration, God pronounces the “law” which is to govern the ordinances of the sanctuary (Compare to 1 Kings 8), first briefly repeating the general rule that the place must be kept holy to the Lord , and then proceeding to specific ordinances commencing with the altar.