Rosh Hashanah, Chapter 4, Mishnah 6. This mishnah deals with the details of the verses recited in the berachos of Malchiyos, Zichronos and Shofaros: how many verses are said, which verses are fit to be said, and what their order is.
The number of verses:
The mishnah states: "Ein omrim pachos me'asarah pesukei malchiyos, asarah shel zichronos, asarah shel shofaros" - one does not say fewer than ten verses of Malchiyos, ten of Zichronos and ten of Shofaros. That is:
Malchiyos - ten verses dealing with the kingship of Hashem.
Zichronos - ten verses of remembrance.
Shofaros - ten mentions of the shofar.
Although ideally one should say ten in each of the berachos, if he said three verses of Malchiyos, three of Zichronos and three of Shofaros, he has fulfilled his obligation.
Which verses may not be mentioned:
One may not mention a verse of Malchiyos, Zichronos or Shofaros that speaks of punishment. The verse recited should not be something negative toward the Jewish people.
The order of the verses:
According to the wording of the mishnah, one begins with verses from the Torah and concludes with verses from the Prophets, and in the middle come verses from the Writings:
Three verses from the Torah.
Three verses from the Writings.
Three verses from the Prophets.
And Rabbi Yosi says - according to the way the matter appears in the wording of our mishnah - that if he concluded with the Torah instead of with the Prophets, he has fulfilled his obligation.
The Gemara's version of Rabbi Yosi's words:
The Gemara establishes that the wording in our mishnah must be revised, and this is how Rabbi Yosi's words should read: ideally one should conclude with the Torah, and this is indeed the practice - three verses from the Torah, three from the Writings, three from the Prophets, and one from the Torah to conclude, ten in all. But if he concluded with a verse from the Prophets instead of from the Torah, he has fulfilled the obligation of the mitzvah.
In summary: In this mishnah we learned the number of verses in each of the berachos - ten ideally and three after the fact; that one does not mention a verse of calamity; and the order of the verses - Torah, Writings and Prophets. We also noted the dispute over the versions of Rabbi Yosi's words: according to the wording of the mishnah one concludes with the Prophets, and according to the Gemara's version one ideally concludes with a verse from the Torah, though after the fact, even if he concluded with a verse from the Prophets, he has fulfilled his obligation.