בַּיּ֣וֹם הַה֡וּא אָשִׂים֩ אֶת־אַלֻּפֵ֨י יְהוּדָ֜ה כְּֽכִיּ֧וֹר אֵ֣שׁ בְּעֵצִ֗ים וּכְלַפִּ֥יד אֵשׁ֙ בְּעָמִ֔יר וְאָ֨כְל֜וּ עַל־יָמִ֧ין וְעַל־שְׂמֹ֛אול אֶת־כָּל־הָעַמִּ֖ים סָבִ֑יב וְיָשְׁבָ֨ה יְרוּשָׁלִַ֥ם ע֛וֹד תַּחְתֶּ֖יהָ בִּירוּשָׁלִָֽם׃ (פ)
В тот день я сделаю вождей Иудейских огней, как кастрюлю огня среди леса, и как факел огня среди снопов; И они пожрут все народы вокруг, справа и слева; И Иерусалим снова будет заселен на своем месте, даже в Иерусалиме.
Rashi
And Chirom made, etc. And Rebbi said, that the כיורות are one and the same as the סירות, as it is stated, “like a pan of fire burning wood,”61Zecharyah 12:6. and similarly, “and he thrust it into the pan.”62I Shmuel 2:14.
HaKtav VeHaKabalah
So that your generations will know that in Sukkos. The clouds of glory began to appear above the people of Israel in Sukkos, as it says (Shemos 12:37): “The children of Israel journeyed from Rameses to Sukkos.” In the Mechilta (12), Rabbi Akiva says: “Sukkos refers solely to the clouds of glory.” It seems that this is why Scripture wrote בסכות with the ו (מלא — full spelling); it teaches us about the place where the clouds of glory first appeared, for the name of the place is always spelled in the full form with the ו — סכות. This is why the cantillation mark over the words כי בסכות is a רביעי, which is a stop, even though it might have been more appropriate to use a מהפך to connect the phrase “that in the sukkos” with the phrase “I caused Bnei Yisroel to dwell” [if it were referring to the booths and not the place]. The commentaries discuss why we were commanded on the 15th of the seventh month, which is the beginning of the cold, rainy season, to leave our permanent dwelling places and stay in a temporary abode. This teaches us that Hashem intended that each Jew should recognize that the honor of his lofty spiritual soul is above the heavens. Its permanent dwelling place is there, and it only came into this world to have a temporary dwelling. The phrase “so that your generations will know” fits well with this explanation, because according to the other explanations it should have said, “so your generations will remember.” The Vilna Gaon answers the question raised by commentators: Why do we celebrate Sukkos in Tishrei? Since it corresponds to the clouds of glory it should be celebrated in Nissan when they were given! The answer is that after they made the Golden Calf the clouds of glory departed, and the clouds returned on the morrow of Yom Kippur, when “Moshe called the whole community of the children of Israel to assemble” (Shemos 35:1). That is why we celebrate Sukkos on the 15th of Tishrei.