Leviticus 6:12-14

12but the fire which is on the altar must be kept burning on it. It must not be extinguished. So the priest must kindle wood on it morning by morning, and he must arrange the burnt offering on it and offer the fat of the peace offering up in smoke on it.

13A continual fire must be kept burning on the altar. It must not be extinguished.

14“‘This is the law of the grain offering. The sons of Aaron are to present it before the Lord in front of the altar,