Leviticus 6:9-13

⁹“Command Aaron and his sons, saying, ‘This is the law of the burnt offering: The burnt offering shall be on the hearth upon the altar all night until morning, and the fire of the altar shall be kept burning on it. ¹⁰And the priest shall put on his linen garment, and his linen trousers he shall put on his body, and take up the ashes of the burnt offering which the fire has consumed on the altar, and he shall put them beside the altar. ¹¹Then he shall take off his garments, put on other garments, and carry the ashes outside the camp to a clean place. ¹²And the fire on the altar shall be kept burning on it; it shall not be put out. And the priest shall burn wood on it every morning, and lay the burnt offering in order on it; and he shall burn on it the fat of the peace offerings. ¹³A fire shall always be burning on the altar; it shall never go out.

The Law of the Grain Offering