Leviticus 8:36

So Aaron and his sons did all things which the Lord commanded by the hand of Moses. Seven days they passed in holy seclusion in the court, seven days they brought the appointed sacrifices and lived on the sacrifice of consecration; what remained of it they did not devote to common or profane use, but they took care to burn it. For seven days they kept holy match, the watch of Jehovah, in the court of the Tabernacle, under the penalty of death. Moses made particularly prominent the symbolic force of this divine watch: it was Jehovah's express commandment.