ויקרא כ״ג:מ״ב
You shall live in booths seven days; all citizens in Israel shall live in booths,
ויקרא כ״ג:מ״ג
in order that future generations may know that I made the Israelite people live in booths when I brought them out of the land of Egypt—I, your God יהוה.
מלבי"ם על ויקרא, אמור ר״ז:א׳
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ערוך השולחן, אורח חיים תרכ״ה:ב׳
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ערוך השולחן, אורח חיים תרכ״ה:ג׳
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שולחן ערוך, אורח חיים תרכ״ה:א׳
On Succot we shall dwell for 7 days etc. Because on Succot I protected the children of Israel. These refer to the clouds of glory who protected them from all the intense heat and the sun of the desert. And it is a Mitzvah to begin building the Succah immediately after Yom Kippur. For if a Mitzvah that comes to one's hands, one should not delay performing it.[Maharil]
ביאור הגר"א על שולחן ערוך אורח חיים תרכ״ה:א׳:א׳
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