Sanhedrin 31B

קלתיה!

she could have burned it. Why did you not accept her testimony?

כיון דאיתחזק בבי דינא, ״איבעיא קלתיה״ לא אמרינן.

Rav Naḥman answered him: Since the promissory note was ratified in court, we do not say that she is deemed credible to nullify its validity because if she had wanted to, she could have burned it. The validity of a ratified document is not nullified without evidence.

איתיביה רבא לרב נחמן: סימפון שיש עליו עדים ⁠– יתקיים בחותמיו. אין עליו עדים, ויצא מתחת ידי שליש, או שיצא אחר חיתום שטרות ⁠– כשר. אלמא שליש מהימן!

Rava raised an objection to the ruling of Rav Naḥman from a baraita: A receipt [simfon] of repayment of a debt upon which witnesses are signed is ratified by means of its signatories. The witnesses testify that these are their signatures, and it is thereby ratified. If there are no witnesses signed on it, but the receipt emerged from the possession of a third party serving as a trustee, or if it emerged after the signing of the documents, i.e., the receipt was written on the promissory note beneath the content of the note and the witnesses’ signatures, it is valid. Rava states his objection: Apparently, the testimony of a third party serving as a trustee is deemed credible, as he can testify that the receipt is valid even if it was not signed by witnesses.

תיובתא דרב נחמן, תיובתא.

The Talmud concludes: The refutation of the opinion of Rav Naḥman is indeed a conclusive refutation.

כי אתא רב דימי, אמר רבי יוחנן: לעולם מביא ראיה וסותר, עד שיסתתם טענותיו ויאמר: קרבו פלוני ופלוני והעידוני.

§ When Rav Dimi came from Eretz Yisrael to Babylonia, he said that R' Yoḥanan said: One can always bring a proof for his claim and overturn the previous verdict, until his claims are stopped up, i.e., until he has no more claims, and he says: Come, so-and-so and so-and-so, and testify on my behalf, in which case those witnesses are not allowed to testify.