Leviticus 6:10-13

10Then the priest must put on his linen robe and must put linen leggings over his bare flesh, and he must take up the fatty ashes of the burnt offering that the fire consumed on the altar, and he must place them beside the altar.

11Then he must take off his clothes and put on other clothes, and he must bring the fatty ashes outside the camp to a ceremonially clean place,

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.