Leviticus 6:12-13
Leviticus 6: 12 to 13
12 And the fire on 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 on it; and he shall burn thereon the fat of the peace offerings.
13 The fire shall ever be burning on the altar; it shall never go out.