The Mishnah in Rosh Hashanah 32a lists the Yom Tov’s berachos and the order in which we must daven on Rosh Hashanah. The Mishnah says in the name of Rabbi Akiva that we begin with the berachah of avos. We then recite, in this order: gevuros (atah gibor); kedushas Hashem; kedushas hayom (we incorporate malchuyos in that berachah); zichronos; and shofros. This is followed by avodah hoda’ah and birchas kohanim (sim shalom). The Gemara there brings a beraisa that cites a source in the Torah for reciting each one of these berachos.
The Achronim discuss two basic questions on this Gemara: First, why does the beraisa need to bring a special pasuk to tell us that we must recite a berachah on the kedushas hayom of Rosh Hashanah? The Gemara in Sukkah 46a derives from the pasuk, “Baruch Hashem, yom yom,” that we must always mention in our davening and bentching the kedushah of that day. Why then would Rosh Hashanah differ from every Shabbos, Yom Tov and Rosh Chodesh when we always mention the kedushas hayom?
Second, why does the beraisa that is discussing the source for reciting the berachos of the Rosh Hashanah amidah need to bring pasukim that are the source for reciting the first three and last three berachos of the amidah? We only change the middle berachos of the amidah, while the first three and the last three are always recited and never change. Why then did the Mishnah have to mention that we recite those berachos, and why did the beraisa deem it necessary to cite a pasuk as the source for it?
The Pnei Yehoshua, in Rosh Hashanah, suggests that the Gemara in Berachos says that one is forbidden to add praise of Hashem to his davening; rather we can only recite the praises that Chazal, based on pasukim, instituted. Since the Torah commanded us to recite malchiyos zichronos and shofros on Rosh Hashanah, one may have thought that we should omit the general praise that we recite in the amidah and only recite the praises of malchiyos zichronos and shofros. Therefore the Mishnah and the beraisa felt that it was necessary to teach us that we do indeed recite the first three berachos of the amidah – even on Rosh Hashanah.
The Aruch LaNer points out that the Pnei Yehoshua’s answer does not explain why the beraisa also included the source for the last three berachos. I would suggest that perhaps once the beraisa must mention the first three and the middle berachos it is not strange for it to continue to mention the last three berachos. The Aruch LaNer suggests that the beraisa is in fact a Tosefta (Rosh Hashanah 2:11) and there the Tosefta does not mention any of the first three or last three berachos – only the middle ones. The Gemara here in Rosh Hashanah added the source for the other berachos based on the beraisa from the Gemara in Megillah, since it was mentioning the source for the other berachos.
The Aruch LaNer concludes that at a later point in time he received the Ritvah’s commentary on Rosh Hashanah and noticed that the Ritvah asks this same question. The Ritvah answers that the Mishnah wrote the first three and last three berachos to teach us that we may not add to those berachos; rather we must recite them as we always do. The Ritvah adds that this is contradictory to our custom to add zachreinu l’chaim, mi kamocha, vekasveinu, and b’sefer chaim. However, he says that our custom is based on the Masechta Sofrim, which is implicit that we should add those prayers into those berachos.
The sefer, Harirai Kedem, suggests that the opposite can be deduced from our Mishnah and beraisa. Maseches Sofrim says that each berachah on Rosh Hashanah is different from the rest of the year. Our Mishnah and beraisa are teaching us that very same idea. Thus it was necessary to write about those berachos as well, in order to teach us that there is a new obligation to add to those berachos.
Regarding the question of why the beraisa needed to write the source for why we mention the kedushas hayom on Rosh Hashanah when we should have already known that we must mention it (as we do on every other Shabbos or Yom Tov), the Harirai Kedem offers this beautiful explanation: It is clear from this that there is a new and separate halacha that requires us to mention the kedushas hayom of Rosh Hashanah on Rosh Hashanah – aside from the general halacha. Based on this we can explain a discrepancy that is found between the mentioning of the kedushas hayom of Rosh Hashanah and that of all the other Yamim Tovim. On all other Yamim Tovim we do not mention the particular Yom Tov; rather we conclude the berachah with “mekadesh Yisrael vehazmanim.” On Rosh Hashanah we conclude the berachah by mentioning the actual essence of the day, for we say, “melech al kol ha’aretz [malchuyos]… mekadesh Yisrael v’Yom Hazikaron.” This exclusive mention of the actual kedushah is only done on Rosh Hashanah because there is a new halacha on Rosh Hashanah to mention the kedushas hayom.