Mishnayos Bava Metzia Perek 9 Mishnah 10

In the case of one who receives a field from another to cultivate for one Sabbatical cycle of seven years culminating with the Sabbatical Year for seven hundred dinars, the Sabbatical Year is included in the tally, despite the fact that he is unable to work the land during that year. If he received it from him to cultivate for seven years for seven hundred dinars, the Sabbatical Year is not included in the number, and he may keep the field for an additional year to take the place of the Sabbatical Year, during which he could not work the land.

הַמְקַבֵּל שָׂדֶה מֵחֲבֵרוֹ לְשָׁבוּעַ אַחַת בִּשְׁבַע מֵאוֹת זוּז, הַשְּׁבִיעִית מִן הַמִּנְיָן. קִבְּלָהּ הֵימֶנּוּ שֶׁבַע שָׁנִים בִּשְׁבַע מֵאוֹת זוּז, אֵין הַשְּׁבִיעִית מִן הַמִּנְיָן: