Talmud for Eruvin 3:8
וְעוֹד אָמַר רַבִּי יְהוּדָה, מַתְנֶה אָדָם עַל הַכַּלְכָּלָה בְּיוֹם טוֹב רִאשׁוֹן וְאוֹכְלָהּ בַּשֵּׁנִי. וְכֵן בֵּיצָה שֶׁנּוֹלְדָה בָרִאשׁוֹן, תֵּאָכֵל בַּשֵּׁנִי. וְלֹא הוֹדוּ לוֹ חֲכָמִים:
And R. Yehudah said further: One stipulates over a basket on the first day of the holiday and eats (from) it on the second. [A basket with fruits of tevel (untithed produce) — one stipulates over it on the first day of Rosh Hashanah, saying: "If today is chol (not yom tov), let this be terumah for those; and if today is kodesh, there is nothing in my words." For terumoth are not separated on yom tov. And the next day he says: "If yesterday was kodesh and today is chol, let what I designated yesterday be terumah for these; and if today is kodesh and yesterday was chol, it is terumah already." And he eats (from) the tithed basket and leaves over the terumah.] And the sages did not concur with him. [The "sages" here are R. Yossi (as above), who holds that they are one sanctity and terumah may not be separated thereon. And this is so only with the two days of Rosh Hashanah, as explained above.] Likewise (R. Yehudah said that) an egg hatched on the first day [of Rosh Hashanah] may be eaten on the second. [For if the first is kodesh, the second is chol; and an egg hatched on yom tov is permitted on chol, there being no hachanah ("preparation") for chol. And if the first is chol and the second kodesh, chol is found, appropriately, to be preparing for kodesh.] And the sages did not concur with him [vis-à-vis the two days of Rosh Hashanah alone, regarding them as one sanctity; but they did concur with him vis-à-vis the two festival days of exile.]