Reference for Eduyot 3:10
שְׁלֹשָׁה דְבָרִים רַבָּן גַּמְלִיאֵל מַחְמִיר כְּדִבְרֵי בֵית שַׁמָּאי. אֵין טוֹמְנִין אֶת הַחַמִּין מִיּוֹם טוֹב לְשַׁבָּת, וְאֵין זוֹקְפִין אֶת הַמְּנוֹרָה בְּיוֹם טוֹב, וְאֵין אוֹפִין פִּתִּין גְּרִיצִין אֶלָּא רְקִיקִין. אָמַר רַבָּן גַּמְלִיאֵל, מִימֵיהֶן שֶׁל בֵּית אַבָּא לֹא הָיוּ אוֹפִין פִּתִּין גְּרִיצִין אֶלָּא רְקִיקִין. אָמְרוּ לוֹ, מַה נַּעֲשֶׂה לְבֵית אָבִיךָ שֶׁהָיוּ מַחְמִירִין עַל עַצְמָן וּמְקִלִּין עַל יִשְׂרָאֵל לִהְיוֹת אוֹפִין פִּתִּין גְּרִיצִין וָחֹרִי:
In three things R. Gamliel takes the stringent view, according to the words of Beth Shammai: Hot foods are not stored from Yom Tov to Shabbath. [Beth Shammai hold that one may not bake (from Yom Tov to Shabbath) unless he has made an eruv tavshilin with a loaf. And he may not cook unless he has made an eruv tavshilin with something cooked. And he may not store food (for warmth) unless he had stored something from the eve of Yom Tov). And Beth Hillel hold that one may bake and cook and store on an eruv of cooked food alone], and a menorah is not assembled on Yom Tov [i.e., a menorah whose parts have been disassembled may not be restored, this being like "building," which obtains with vessels. And Beth Hillel hold that "building" does not obtain with vessels], and thick loaves are not baked (on Yom Tov), but only thin ones. [Beth Shammai hold that much bread is not baked on Yom Tov because of "exertion." And Beth Hillel say that it is baked, for when there is more bread it bakes better.] R. Gamliel said: From the days of Beth Shammai they did not bake thick loaves but only thin ones. They said to him: What shall we do for your father's house, who were stringent with themselves and lenient with Israel, allowing them to bake thick breads and chari? [(ample dough baked over coals.) The halachah is not in accordance with R. Gamliel in all of his stringencies according to the words of Beth Shammai.]