סימן קלה סעיף ח

שֵׁנָה, אֲפִלּוּ אַרְעַי, מִדִּינָא צְרִיכָה סֻכָּה. וְכֵן עוֹשִׂין הַמְדַקְדְּקִין בַּמִצְוֹת, שֶׁאֲפִלּוּ שְׁנַת אַרְעַי אֵינָם יְשֵׁנִים חוּץ לַסֻּכָה. וְעַתָּה שֶׁנּוֹהֲגִים הַרְבֵּה לְהָקֵל בַּשֵׁנָה, כָּתְבוּ הָאַחֲרוֹנִים, זִכְרוֹנָם לִבְרָכָה, כַּמָּה טְעָמִים, לְלַמֵּד קְצָת זְכוּת עֲלֵיהֶם. אֲבָל כָּל יְרֵא שָׁמַיִם, רָאוּי לוֹ לְהַחְמִיר וְלַעֲשׂוֹת סֻכָּה, שֶׁיוּכַל לָדוּר שָׁם עִם אִשְׁתּוֹ, כְּמוֹ שֶׁהוּא דָר בְּכָל הַשָּׁנָה כֻּלָּהּ, אִם אֶפְשָׁר לוֹ. וּלְכָל הַפָּחוֹת שֶׁתְּהֵא רְאוּיָה לִישֹׁן שָׁם הוּא לְבַדּוֹ. וְאִם אֵינָהּ כֵּן, אֲפִלּו בְדִיעֲבַד, הִיא פְסוּלָה.

Sleeping, or even taking a nap, according to Halachah, must be in the sukkah. And this is the practice of those who are scrupulous in observing the mitzvos; they, indeed, do not even take a nap outside the sukkah. But nowadays, many people are lenient with regard to sleeping [in the sukkah]. The later authorities, of blessed memory, wrote a number of reasons to justify this leniency to an extent. However, every God-fearing person, should be stringent and build a sukkah in which he and his wife can dwell in the same manner they live the entire year, if possible. At minimum, [the sukkah] should be suitable for him to sleep in, for if it does not meet these standards it is not valid, even post factum⁹Mishnah Berurah writes, “In places where the climate is cold [during this time of year], you still fulfill your obligation by eating in the sukkah even though you are unable to sleep there. Since it is impossible otherwise, it is therefore considered that you are living in the sukkah in the same manner as in your home. (Ibid 640:18, 20) [even after it was already built].

תנא דבי אליהו כל השונה הלכות בכל יום מובטח לו שהוא בן העולם הבא שנאמר הליכות עולם לו אל תקרי הליכות אלא הלכות (נדה ע"ג.)