(11) This is the ritual of the sacrifice of well-being that one may offer to God: (12) If he offers it for thanksgiving, he shall offer unleavened cakes with oil mixed in, unleavened wafers spread with oil, or cakes of fine flour with oil mixed in, well-soaked. (13) Beside these cakes, he may offer loaves of leavened bread for his thanksgiving sacrifice of well-being.
(ה) וְהָאֵ֨שׁ עַל־הַמִּזְבֵּ֤חַ תּֽוּקַד־בּוֹ֙ לֹ֣א תִכְבֶּ֔ה וּבִעֵ֨ר עָלֶ֧יהָ הַכֹּהֵ֛ן עֵצִ֖ים בַּבֹּ֣קֶר בַּבֹּ֑קֶר וְעָרַ֤ךְ עָלֶ֙יהָ֙ הָֽעֹלָ֔ה וְהִקְטִ֥יר עָלֶ֖יהָ חֶלְבֵ֥י הַשְּׁלָמִֽים׃ (ו) אֵ֗שׁ תָּמִ֛יד תּוּקַ֥ד עַל־הַמִּזְבֵּ֖חַ לֹ֥א תִכְבֶֽה׃ (ס)
(5) The fire on the altar shall be kept burning, not to go out: every morning the priest shall feed wood to it, lay out the burnt offering on it, and turn into smoke the fat parts of the offerings of well-being. (6) A perpetual fire shall be kept burning on the altar, not to go out.
רַבֵּנוּ הַזָּקֵן סִפֵּר: מֵהַתּוֹרוֹת שֶׁאָמַר מוֹרִי לְפָנַי בִּיחִידוּת, הָיְתָה תּוֹרָה עַל הַפָּסוּק אֵשׁ תָּמִיד תּוּקַד עַל הַמִּזְבֵּחַ לֹא תִכְבֶּה, דַּהֲגַם שֶׁהָאֵשׁ יוֹרֵד מִלְמַעְלָה בְּאִתְעֲרוּתָא דִלְעֵילָּא, מִצְוָה לְהָבִיא מִן הַהֶדְיוֹט, כִּי בְּאִתְעַרוּתָא דִלְתַתָּא אִתְעַרוּתָא דִלְעֵילָא, כִּי רוּחַ אַיְיתֵי רוּחַ וְאַמְשִׁיךְ רוּחַ, רוּחַ מִלְּמַטָּה אַיְיתֵי רוּחַ מִלְעֵילָּא, וְאַמְשִׁיךְ רוּחַ מִלְעֵילָּא וּלְעֵילָּא. ...
וְהַהַקְרָבָה עַצְמָהּ אֵינָהּ מַסְפֶּקֶת, וּצְרִיכִים לְהַבְעִיר אֵשׁ עַל הַקָּרְבָּן אֲשֶׁר מִכֶּם, וְאֵשׁ זֶה לֹא תִכְבֶּה, שֶׁהִיא מְכַבָּה אֶת הַ"לֹא".
אֶת הַתּוֹרָה הַזֹּאת אָמַר מוֹרִי לְפָנַי עֶשֶׂר פְּעָמִים, כְּדֵי לְחָקְקָהּ בְּעֶשֶׂר כֹּחוֹת נַפְשִׁי. וַיֹּאמֶר לִי, אַתָּה תַּלְמִידִי הִנְּךָ נִצְרָךְ לְהָאֵשׁ תָּמִיד, לְפִי שֶׁעָלֶיךָ הוּטַל לְכַבּוֹת לֹא גָּדוֹל. אַתָּה תְכַבֶּה אֶת הַלֹּא וְהַשֵּׁם יִתְבָּרֵךְ יַהֲפוֹך אֶת הַלֹּא לְהֵן.
The Alter Rebbe [Rabbi Shneur Zalman of Liadi, 1745-1812] once related:
“One of the teachings that my master [the Maggid of Mezritch, c.1710-1772] imparted to me privately was an exposition of the verse, ‘A perpetual fire shall be kept burning on the altar; not to go out.’
Despite the fact that God's fire would descend from above [to consume the sacrifices], there is nonetheless an obligation to kindle ordinary fire on the altar. The kindling from below arouses a kindling from above; a spirit from below calls forth a spirit from above, which is drawn down from the highest realms. ...
Merely bringing the sacrificial offering is insufficient. One must also light a fire for the offering that comes from within oneself; this fire may not be extinguished. Rather, this fire extinguishes the 'No'.
My master delivered this teaching to me ten times in order to engrave it in the ten faculties of my soul. He told me: ‘You, my student, will need a perpetual fire, in order to extinguish a great No. But when you extinguish the No, the Lord of Blessing will transform the No into a Yes.’"