Leviticus 6:13 (KJV)

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.

And this is the law of the meat offering: the sons of Aaron shall offer it before the Lord, before the altar.

And he shall take of it his handful, of the flour of the meat offering, and of the oil thereof, and all the frankincense which is upon the meat offering, and shall burn it upon the altar for a sweet savour, even the memorial of it, unto the Lord.