- באחד בתשרי ראש השנה לשנים
The Mishnah stated באחד בתשרי ראש השנה לשנים – On the first of Tishrei is the Rosh Hashanah for reckoning the years. The Gemara here asks what law this is referring to, and a number of answers are given. Rav Pappa said it was for שטרות – for the dating of documents, and the Gemara clarifies that it is for dating documents according to the years of the non-Jewish king’s reign. Rebbe Zeira said that Tishrei is the Rosh Hashanah לתקופה, in relation to the seasons. Rashi explains that we calculate the solar and lunar seasons based on a starting point which assumes the creation of the world began in Tishrei. This opinion goes according to Rebbe Eliezer, who said בתשרי נברא העולם – that the world was created in Tishrei. Rav Nachman bar Yitzchak said that the first of Tishrei is the Rosh Hashanah לדין – for judgment, for it is written, "מרשית השנה ועד אחרית שנה" – The eyes of Hashem are on it from the beginning of the year until the end of the year. This means מראשית שנה נידון מה יהא בסופה –from the beginning of the year, judgment is issued regarding what will occur at the end.
- כי חק לישראל הוא משפט לאלקי יעקב
The Gemara continues and asks how we know that the passuk "מרשית השנה ועד אחרית שנה" is referring to Tishrei, and answers, for it is written: "תקעו בחדש שופר בכסה ליום חגנו" – Blow a shofar at the moon’s renewal, when the moon is covered on our festive day. Now, on which chag is the moon covered? You must say that this is Rosh Hashanah, for Rosh Hashanah is the only chag that falls at the beginning of the month, when the moon is hidden from view. And it is written in the next passuk: "כי חק לישראל הוא משפט לאלקי יעקב" – Because it is a statute for Yisroel, a judgment day unto the G-d of Yaakov. We therefore see that Rosh Hashanah is a day of judgment. The Rabbis taught in a Baraisa that this passuk is coming to teach שאין בית דין של מעלה נכנסין לדין אלא אם כן קידשו בית דין של מטה את החדש – that the Heavenly Court above does not enter into judgment unless the court below has sanctified the moon. Rashi explains כי חק לישראל הוא - that when Yisroel has established the legal status of the month through קידוש החודש , then משפט לאלקי יעקב -Hashem begins His judgment of the world.
- באחד בתשרי ראש השנה ליובלות
The Mishnah had stated that the first of Tishrei is the Rosh Hashanah for יובלות – the Yovel years. The Gemara asks how this can be, for the Rosh Hashanah for Yovel is on the tenth of Tishrei, which is Yom Kippur, as it is written regarding the onset of the Yovel year: "ביום הכפרים תעבירו שופר" – on Yom Kippur you shall sound the shofar. How can our Mishnah state that it begins on the first of Tishrei? The Gemara answers that the Tanna is Rebbe Yishmael ben Beroka, for it was taught in a Baraisa: When the passuk states: "וקדשתם את שנת החמשים שנה" – And you shall sanctify the fiftieth year, what is it teaching? Do we not know that Yovel is the fiftieth year? The answer is that since in the previous passuk it is stated: On Yom Kippur you shall sound the shofar, it could be thought that the year is only sanctified from Yom Kippur and on. The Torah therefore states: "וקדשתם את שנת החמשים" – You shall sanctify the fiftieth year. מלמד שמתקדשת והולכת מתחילתה – This teaches that the year becomes sanctified from its beginning, meaning from the first of Tishrei. From the first of Tishrei it was forbidden to work the land, and while slaves could not yet return to their homes, they were not enslaved to their masters. Rather, they would eat and drink and rejoice, with crowns on their head.