Leviticus 6:9-13
9 “Give Aaron and his sons this command: ‘These are the regulations for the burnt offering: The burnt offering is to remain on the altar hearth throughout the night, till morning, and the fire must be kept burning on the altar.
10 The priest shall then put on his linen clothes, with linen undergarments next to his body, and shall remove the ashes of the burnt offering that the fire has consumed on the altar and place them beside the altar.
11 Then he is to take off these clothes and put on others, and carry the ashes outside the camp to a place that is ceremonially clean.
12 The fire on the altar must be kept burning; it must not go out. Every morning the priest is to add firewood and arrange the burnt offering on the fire and burn the fat of the fellowship offerings on it.
13 The fire must be kept burning on the altar continuously; it must not go out.