ספֿרי מצוות אויף ויקרא 6:6

That He prohibited us from extinguishing fire on top of the altar. And that is His, may He be exalted, saying, "A perpetual fire shall be kept burning on the altar, not to go out" (Leviticus 6:6). And in the [Sifra] (Sifra, Tzav, Chapter 10:7): "One who extinguishes [it] transgresses a negative commandment." And anyone who transgresses this negative commandment and extinguishes even one of the coals of the altar is lashed. And the regulations of this commandment have already been explained in the tenth [chapter] of Zevachim. (See Parashat Tzav; Mishneh Torah, Daily Offerings and Additional Offerings 2.)