Related for Rosh Hashanah 2:7
רֹאשׁ בֵּית דִּין אוֹמֵר מְקֻדָּשׁ, וְכָל הָעָם עוֹנִין אַחֲרָיו מְקֻדָּשׁ מְקֻדָּשׁ. בֵּין שֶׁנִּרְאָה בִזְמַנּוֹ בֵּית שֶׁלֹּא נִרְאָה בִזְמַנּוֹ, מְקַדְּשִׁין אוֹתוֹ. רַבִּי אֶלְעָזָר בְּרַבִּי צָדוֹק אוֹמֵר, אִם לֹא נִרְאָה בִזְמַנּוֹ, אֵין מְקַדְּשִׁין אוֹתוֹ, שֶׁכְּבָר קִדְּשׁוּהוּ שָׁמָיִם:
The head of beth-din says: "It is sanctified," [it being written (Leviticus 23:44): "And Moses declared the festivals of the L-rd" — whence it is derived that the head of beth-din says: "It is sanctified."], and all the people respond: "It is sanctified; it is sanctified," [it being written (Ibid. 3): "…the festivals of the L-rd which you shall call them" (otham) — read it "atem" ("you"), it being written without the vav (i.e., you declare the New Moon). ("It is sanctified; it is sanctified":) twice, it being written (Ibid.): "callings of holiness," two callings.] Whether it is seen in its time [on the night of the thirtieth] or not seen in its time, it is sanctified. R. Elazar b. Tzaddok says: If it is not seen in its time, [and the night of Rosh Chodesh is set as the night of the thirty-first], it is not sanctified, having already been sanctified by Heaven. [For the sanctification of the moon is not obligatory, it being written (Ibid. 25:10): "And you shall sanctify the fiftieth year" — You sanctify years (it being incumbent upon beth-din to say that the month is sanctified in the year of the Jubilee), but you do not sanctify months, (it not being incumbent upon beth-din to say that the month is sanctified. And when it is seen in its time, it is sanctified because it requires "strengthening." The halachah is in accordance with R. Elazar b. R. Tzaddok.]