Shevuot 26A

חדא מינייהו רב פפא אמרה.

Rav Pappa said one of those statements, not Abaye.

רבי ישמעאל אומר: אינו חייב אלא על העתיד לבא. תנו רבנן: ״להרע או להיטיב״⁠ – אין לי אלא דברים שיש בהן הרעה והטבה; שאין בהן הרעה והטבה מנין? תלמוד לומר: ״או נפש כי תשבע לבטא בשפתים״.

§ The Mishnah teaches that R' Yishmael says: One is liable only for an oath on an utterance taken about the future. A baraita states with regard to an oath on an utterance: From the verse: “Or if anyone take an oath clearly with his lips to do evil, or to do good” (Leviticus 5:4), I have derived only that one is liable for an oath on an utterance with regard to matters to which doing evil and doing good apply. From where do I derive that one is liable for an oath on an utterance with regard to matters to which doing evil and doing good do not apply? The verse states: “Or if anyone take an oath clearly with his lips,” which includes other matters.

אין לי אלא להבא, לשעבר מנין? תלמוד לומר: ״לכל אשר יבטא האדם בשבעה״. דברי רבי עקיבא. רבי ישמעאל אומר: ״להרע או להיטיב״⁠ – להבא.

I have derived only that one is liable for oaths referring to the future. From where do I derive that one is liable for oaths referring to the past? The verse subsequently states: “Whatsoever it be that a man should utter clearly with an oath” (Leviticus 5:4); this is the statement of R' Akiva. R' Yishmael says: The verse states: “To do evil, or to do good,” referring exclusively to oaths about the future.

אמר לו רבי עקיבא: אם כן, אין לי אלא דברים שיש בהן הטבה והרעה, דברים שאין בהן הרעה והטבה מנין? אמר לו: מרבוי הכתוב. אמר לו: אם ריבה הכתוב לכך, ריבה הכתוב לכך!

The baraita continues: R' Akiva said to him: If so, then I have derived only that one is liable for an oath on an utterance with regard to matters to which doing evil and doing good apply. From where do I derive that one is liable for an oath on an utterance with regard to matters to which doing evil and doing good do not apply? R' Yishmael said to R' Akiva in response: It is derived from an amplification of the meaning of the verse. R' Akiva said to him: If the verse is amplified for this, i.e., to extend the halakha of an oath on an utterance to matters that do not involve doing evil or good, the verse is amplified for that, i.e., oaths about the past.