Reference for Sukkah 2:7
מִי שֶׁהָיָה רֹאשׁוֹ וְרֻבּוֹ בַסֻּכָּה, וְשֻׁלְחָנוֹ בְתוֹךְ הַבַּיִת, בֵּית שַׁמַּאי פּוֹסְלִין, וּבֵית הִלֵּל מַכְשִׁירִין. אָמְרוּ לָהֶן בֵּית הִלֵּל לְבֵית שַׁמַּאי, לֹא כָךְ הָיָה מַעֲשֶׂה, שֶׁהָלְכוּ זִקְנֵי בֵית שַׁמַּאי וְזִקְנֵי בֵית הִלֵּל לְבַקֵּר אֶת רַבִּי יוֹחָנָן בֶּן הַחוֹרָנִי, וּמְצָאוּהוּ שֶׁהָיָה יוֹשֵׁב רֹאשׁוֹ וְרֻבּוֹ בַסֻּכָּה, וְשֻׁלְחָנוֹ בְתוֹךְ הַבַּיִת, וְלֹא אָמְרוּ לוֹ דָבָר. אָמְרוּ לָהֶן בֵּית שַׁמַּאי, מִשָּׁם רְאָיָה, אַף הֵם אָמְרוּ לוֹ, אִם כֵּן הָיִיתָ נוֹהֵג, לֹא קִיַּמְתָּ מִצְוַת סֻכָּה מִיָּמֶיךָ:
If one's head and most of his body were in the succah, and his table in his house — Beth Shammai rule that it is pasul, and Beth Hillel, that it is kasher. [The halachah is in accordance with Beth Shammai, whether it is a large succah and he is sitting at the entrance of the succah with his table in his house, or it is a small succah, which does not accommodate his head and most of his body — both are forbidden — a decree, lest he "be drawn" after his table.] Beth Hillel said to Beth Shammai: "Did it not happen that the elders of Beth Shammai and the elders of Beth Hillel went to visit R. Yochanan b. Hachorani and found him sitting with his head and most of his body in the succah and his table in the house, and they said nothing to him?" Beth Shammai rejoined: "Can you offer proof from there? They did, indeed, tell him: 'If this is how you have (always) deported yourself, you have never fulfilled the mitzvah of succah in all of your days!'"