וכי הזאה יש לנו אמר ליה רמי בר חמא לא ליחוש ליה לסבא אדהכי אתא רב עמרם אמר להו הכי אמר רב טמא מת טובל ואוכל בתרומת חוצה לארץ
But do we have sprinkling of the ashes of the red heifer? Since without such sprinkling one remains impure after contact with a corpse, how does it help to immerse in a ritual bath? Rami bar Ḥama said to him: Shouldn’t Rav Naḥman be concerned for the opinion of the old man, i.e., Rav Amram? Wouldn’t it be better to wait until he returns before answering? Meanwhile, Rav Amram came back. He said to them that this is what Rav says: One who became impure with impurity imparted by a corpse may immerse and partake of teruma from produce grown outside of Eretz Yisrael.
ולית הלכתא כוותיה דאמר מר זוטרא משמיה דרב ששת טמא שרץ טובל ואוכל בתרומת חוצה לארץ ולית הלכתא כוותיה:
The Gemara comments: But the halakha is not in accordance with his opinion. Mar Zutra said in the name of Rav Sheshet: One who became impure through contact with the carcass of a creeping animal may immerse in a ritual bath and partake of teruma from produce grown outside of Eretz Yisrael. But the halakha is not in accordance with his opinion.
בכור נאכל שנה בשנה כו': מדקאמר נולד בו מום בתוך שנתו למימרא דלשנה דידיה מנינן מנא הני מילי
§ The mishna teaches: The firstborn animal is eaten year by year, i.e., within its first year, whether it is blemished or unblemished. The Gemara comments: From the fact that the mishna says: If a blemish developed within its first year, rather than within the first year, that is to say that we count according to its year, not by the calendar year. In other words, the year is calculated from the day of the animal’s birth. From where is this matter derived?
דאמר רב יהודה אמר רב דאמר קרא (דברים טו, כ) לפני ה' אלהיך תאכלנו שנה בשנה איזוהי שנה שנכנסת בחברתה הוי אומר שנה של בכור
It is derived from a verse, as Rav Yehuda says that Rav says that the verse states: “You shall eat it before the Lord your God, year by year [shana beshana] in the place that the Lord shall choose, you and your household” (Deuteronomy 15:20). The phrase “shana beshana,” which can also be translated as: A year in a year, indicates that the verse is referring to one year that enters another year. Which type of year enters another year? You must say that this is speaking of the year of the firstborn animal, which enters the following calendar year, since if the animal is born in the middle of the year, its first year includes part of the subsequent calendar year.
דבי רב תנא שנה בשנה יום אחד בשנה זו ויום אחד בשנה זו לימד על הבכור שנאכל לשני ימים ולילה אחד
The school of Rav taught that there is a different halakha derived from the phrase “year by year.” This phrase indicates that it may be eaten on one day of this year and one day of that next year. The verse thereby taught with regard to an unblemished firstborn animal, which is sacrificed in the Temple, that it is eaten for two days and one night, like a peace offering.
דבי רב מנא להו ילפי מקדשים וקדשים גופייהו מנלן אמר רב אחא בר יעקב אמר קרא (ויקרא יב, ו) כבש בן שנתו שנתו שלו ולא שנה של מנין עולם
The Gemara asks: From where does the school of Rav derive the halakha that a firstborn must be eaten within its own year and that its year is not calculated according to the calendar year? They derive it from the halakha of other sacrificial animals, whose age is counted from their birth rather than by the calendar year. And with regard to the other sacrificial animals themselves, from where do we derive that their age is counted from their birth? Rav Aḥa bar Yaakov says that the verse states: “And when the days of her purification are fulfilled, for a son or for a daughter, she shall bring a lamb in its first year for a burnt offering, and a pigeon or a dove for a sin offering, to the door of the Tent of Meeting, to the priest” (Leviticus 12:6). This description of the lamb is referring to its own year, and not a year of the counting of the world.
ורב נאכל לשני ימים ולילה אחד מנא ליה נפקא ליה (במדבר יח, יח) מובשרם יהיה לך כחזה התנופה וכשוק הימין הקישו הכתוב לחזה ושוק של שלמים מה להלן שני ימים ולילה אחד אף כאן שני ימים ולילה אחד
The Gemara asks: And Rav, from where does he derive that a firstborn is eaten for two days and one night? The Gemara answers: He derives it from a verse in which Moses spoke to Aaron and his sons with regard to eating the firstborn: “And their flesh shall be yours, as the breast of waving and as the right thigh, it shall be yours” (Numbers 18:18). The verse thereby juxtaposed the halakha of the firstborn with the breast and thigh of a peace offering. Just as there, it may be eaten for two days and one night, as stated explicitly in a verse (see Leviticus 7:16), so too here, a firstborn may be eaten for two days and one night.