Leviticus 6:9, 12-13

“Command Aaron and his sons, saying, This is the law of the burnt offering. The burnt offering shall be on the hearth on the altar all night until the morning, and the fire of the altar shall be kept burning on it.

The fire on the altar shall be kept burning on it; it shall not go out. The priest shall burn wood on it every morning, and he shall arrange the burnt offering on it and shall burn on it the fat of the peace offerings. Fire shall be kept burning on the altar continually; it shall not go out.