And the LORD spake unto Moses, saying,
“Command Aaron and his sons, saying, ‘This is the law of the burnt offering: It is the burnt offering, because of the burning upon the altar all night unto the morning, and the fire of the altar shall be burning in it. And the priest shall put on his linen garment, and his linen breeches shall he put upon his flesh, and take up the ashes which the fire hath consumed with the burnt offering on the altar, and he shall put them beside the altar. And he shall put off his garments, and put on other garments, and carry forth the ashes without the camp unto a clean place.  And the fire upon the altar shall be burning in it; it shall not be put out: and the priest shall burn wood on it every morning, and lay the burnt offering in order upon it; and he shall burn thereon the fat of the peace offerings. The fire shall ever be burning upon the altar; it shall never go out.'”
Leviticus 6:8-13