Rosh Hashanah 13A

ודלמא לא עייל כלל, וקאמר רחמנא תשמט ותיזיל עד חג הסוכות!

But perhaps the verse is referring to produce that did not grow at all during the 7th year, and nevertheless, God states in the Torah that all the halakhot of the Sabbatical Year continue to apply until the festival of Sukkot of the 8th year.

לא סלקא דעתך, דכתיב: ״וחג האסיף בצאת השנה״, מאי ״אסיף״? אילימא: חג הבא בזמן אסיפה ⁠— הכתיב: ״באספך״.

The Talmud answers: It should not enter your mind to say this, as it is written: “And the festival of gathering, which is at the end of the year, when you have gathered in your labors out of the field” (Exodus 23:16). What is the meaning of “gathering”? If we say that it means: A Festival that comes at the time of gathering the crops, isn’t it already written: “When you have gathered in your labors”? There is no need to repeat this a second time.

אלא מאי ״אסיף״⁠ — קציר. וקים להו לרבנן דכל תבואה שנקצרה בחג, בידוע שהביאה שליש לפני ראש השנה, וקא קרי לה ״בצאת השנה״.

Rather, what is meant here by “gathering”? It means harvesting. And the rabbis have an accepted tradition that any grain that reaches full growth so that it is harvested on the festival of Sukkot is known to have reached 1/3rd of its growth before Rosh HaShana, and the Torah calls that period of the year until Sukkot “at the end of the year,” thereby indicating that it is still subject to the halakhot governing the previous year.

אמר ליה רבי ירמיה לרבי זירא: וקים להו לרבנן בין שליש לפחות משליש? אמר ליה: לאו אמינא לך לא תפיק נפשך לבר מהלכתא? כל מדות חכמים ⁠— כן הוא.

§ R' Yirmeya said to R' Zeira: And are the rabbis able to discern precisely between produce that reached 1/3rd of its growth and produce that reached less than 1/3rd of its growth? R' Zeira said to him: Do I not always tell you that you must not take yourself out of the bounds of the halakha? All the measures of the rabbis are like this; they are precise and exact.