Exodus 29:37
Seven days thou shalt make an atonement for the altar, and sanctify it; and it shall be an altar most holy: whatsoever toucheth the altar shall be holy. Seven days thou shalt make an atonement for the altar, and sanctify it; and it shall be an altar most holy: whatsoever toucheth the altar shall be holy.
The direction concerning the altar was given to Israel in the wilderness as part of their divine instruction, and that instruction came through Christ Himself. It was not merely ceremonial detail but a revelation of the terms of salvation. As such it provides the education of greatest value, teaching how sinners are reconciled and made holy.