Reference for Eruvin 3:6
רַבִּי אֱלִיעֶזֶר אוֹמֵר, יוֹם טוֹב הַסָּמוּךְ לְשַׁבָּת, בֵּין מִלְּפָנֶיהָ וּבֵין מִלְּאַחֲרֶיהָ, מְעָרֵב אָדָם שְׁנֵי עֵרוּבִין וְאוֹמֵר, עֵרוּבִי הָרִאשׁוֹן לַמִּזְרָח, וְהַשֵּׁנִי לַמַּעֲרָב. הָרִאשׁוֹן לַמַּעֲרָב, וְהַשֵּׁנִי לַמִּזְרָח. עֵרוּבִי הָרִאשׁוֹן, וְהַשֵּׁנִי כִּבְנֵי עִירִי. עֵרוּבִי הַשֵּׁנִי, וְהָרִאשׁוֹן כִּבְנֵי עִירִי. וַחֲכָמִים אוֹמְרִים, מְעָרֵב לְרוּחַ אַחַת, אוֹ אֵינוֹ מְעָרֵב כָּל עִקָּר. אוֹ מְעָרֵב לִשְׁנֵי יָמִים, אוֹ אֵינוֹ מְעָרֵב כָּל עִקָּר. כֵּיצַד יַעֲשֶׂה. מוֹלִיכוֹ בָרִאשׁוֹן, וּמַחְשִׁיךְ עָלָיו וְנוֹטְלוֹ וּבָא לוֹ. בַּשֵּׁנִי מַחְשִׁיךְ עָלָיו וְאוֹכְלוֹ. וְנִמְצָא מִשְׂתַּכֵּר בַּהֲלִיכָתוֹ וּמִשְׂתַּכֵּר בְּעֵרוּבוֹ. נֶאֱכַל בָּרִאשׁוֹן, עֵרוּבוֹ לָרִאשׁוֹן וְאֵינוֹ עֵרוּב לַשֵּׁנִי. אָמַר לָהֶם רַבִּי אֱלִיעֶזֶר, מוֹדִים אַתֶּם לִי שֶׁהֵן שְׁתֵּי קְדֻשּׁוֹת:
R. Eliezer says: Yom Tov close to Shabbath, both (immediately) before it or after it — one places two eruvin and says: "My first eruv is to the east, and the second, to the west" (or) "My first to the west and the second to the east." [If he had to go in one direction on the first day, and in a different direction the second day, he can place an eruv to the east and to the west on the eve of the first day and say: "Let my eruv to the east effect acquisition for me today for tomorrow, and let my eruv to the west effect acquisition for me ben hashmashoth tomorrow for the second day." For R. Eliezer holds that Shabbath and yom tov are not regarded as one long day, but as two separate sanctities, and the ben hashmashoth of the first effects acquisition for itself and not for the second day.] "My eruv is (for) the first (day); and on the second, as the people of my city." [That is, if he needed to go only on the first day, and on the second, he did not need to move from his spot, and he does not wish to lose two thousand from his tchum in either direction, he places one eruv in the direction he wishes to go the first day, and he says: "Let his eruv effect acquisition for me for tomorrow, and on the second day, I shall be as the men of my city," who did not make an eruv. Or, if he had to go on the second day and not on the first, he says: "Let this eruv effect acquisition for me ben hashmashoth tomorrow, and on the first day I shall be as the men of my city."] And the sages say: He makes an eruv in one direction (for both days) or he does not make an eruv at all; or he makes an eruv for two days or he does not make an eruv at all. [This is the same as "in one direction" above. Why need it be mentioned? This is what the rabbis are saying to R. Eliezer: Do you not concur that for one day he makes an eruv either in one direction or not at all? For he cannot say: "Let my eruv be a half day to the east and a half day to the west." For two days, too — that is, for Shabbath and yom tov — he makes an eruv as for one day or he does not make an eruv at all. For the rabbis are in doubt as to whether or not Shabbath and yom tov are regarded as one day. So they rule stringently here — that he may not make an eruv in two directions, in that they might constitute one sanctity — and stringently there, saying below that if it were eaten on the first day, there is no eruv for the second day, in that they might constitute two distinct sanctities and not be regarded as one long day.] What does he do (if he desires the eruv for two days in one direction)? He [the messenger] takes it on the first day [i.e., on the eve of the yom tov before Shabbath], and he waits for dark [until the eruv effects acquisition.] Then he takes it and returns, [lest it go lost and he have no eruv for the second day, as it is taught: "If his eruv were eaten on the first day, it is an eruv for the first day but not for the second."], and on the second day he waits for dark and eats it. [He takes it back on the second day. For it is ruled that if one makes an eruv with a loaf on the first day and he wishes to make an eruv with a loaf on the second day, he must do so with the very same eruv that he designated as such the day before (saying nothing), but not with a different loaf. For he would have to designate it as an eruv, and this would constitute preparation from yom tov to Shabbath.] So that he is found to gain in his going [That is, he effects acquisition for going (beyond the tchum) the next day], and (he is found) to gain in his eruv, [which he eats. And on yom tov after Shabbath, where this is not possible, he takes it there on the first day and does not eat it, and he returns there on the second day to see if it is still there. (If it is,) he waits for dark, after which he may eat it if he so desires.] If it were eaten on the first day, it is an eruv for the first but not for the second. R. Eliezer said to them: You concur with me that they are two (distinct) sanctities. [For you say that if his eruv were eaten on the first day, it does not serve for the second day. And if it were one sanctity, it would be reckoned as one long day, so that the ben hashmashoth of the first day would effect acquisition for both days. Since they are two sanctities, then, he can also make an eruv in two directions! And the rabbis follow the stringent ruling in both instances, as stated above, being in doubt (as to whether they are one or two sanctities.) The halachah is in accordance with R. Eliezer, that Shabbath and yom tov are two sanctities.]