Shevuot 49A

לכל מגלגלין, חוץ משכיר ⁠– שאין מגלגלין. רב חסדא אמר: לכל אין מקילין, חוץ משכיר ⁠– דמקילין. מאי בינייהו? איכא בינייהו לפתוח לו.

Any oath, including one incurred by rabbinic law, may be extended to render the person who takes it liable to take an additional oath, except for the oath of a hired worker, which may not be extended, since the hired worker’s oath was instituted only to alleviate the concerns of the employer. Rav Ḥisda says: For everyone, the rabbis are not lenient, in that they extend any oath they incur to impose upon them additional oaths, except for a hired worker, for whom they are lenient. The Talmud asks: What is the difference between the rulings of Rav Huna and Rav Ḥisda? The Talmud answers: There is a practical difference between them as to whether the court initiates extending an oath for him, i.e., even when the other litigant has not suggested it, the court extends the original oath to include an oath about other claims.

והשביעית משמטת כו׳. מנא הני מילי? אמר רב גידל אמר רב, דאמר קרא: ״וזה דבר השמטה״⁠ – ואפילו דיבור משמטת.

§ The Mishnah teaches: The Sabbatical Year abrogates the obligation to take an oath about a debt, just like it abrogates a debt. The Talmud asks: From where is this matter derived? Rav Giddel says that Rav says: It is derived from the fact that the verse states: “And this is the matter [devar] of the release: Every creditor should release that which he has lent to his neighbor; he should not exact it of his neighbor and his brother, because YHWH’s release has been proclaimed” (Deuteronomy 15:2). Since the word devar also means statement, this teaches that the Sabbatical Year releases, i.e., abrogates, even a statement, i.e., an oath.