Study Bava Batra folio 164A with parallel Hebrew-English text, traditional commentary, and modern study tools. Free access to Babylonian Talmud online.
Text Excerpt
ואם תאמר: מוחק וחוזר ומוחק! אינו דומה נמחק פעם אחת, לנמחק שתי פעמים.
And if you say: There is a possibility of forgery with such a document, as the holder of the document can erase the original writing on the paper, then write the text of the document and have witnesses sign on the part that had been erased, then erase the document text once again, substituting for it a text that is more to his advantage, leaving the original signatures in place, this is not a valid argument. Paper that has been erased once is not similar in appearance to paper that has been erased twice. It will be seen that the signatures are on a place that had been erased once and that the text is written on a place that had been erased twice, and the forgery will be noticed.
The Talmud suggests: But let there be a concern that perhaps the holder of the document will initially, after the entire original document, including the signatures, has been erased, but before the second one is written, throw some ink on the place where the witnesses are to sign under the text of the second document, and then erase that ink. He will do this so that when, after the witnesses have signed, he then erases the document text and writes a false text, it will emerge that both this, the new document’s text, and that, the signatures, will be on paper that had been erased twice.
אמר אביי, קסבר רב: אין העדים חותמין על המחק, אלא אם כן נמחק בפניהם.
Abaye said in response: Rav holds that witnesses may not sign a document written over an erasure unless the paper was erased in their presence, i.e., unless they saw the paper after its old text had been erased, before the new text was written. They will then see that the place where they are to sign has been erased twice, while the place where the document is to be written has been erased only once. They will realize that this leaves open an opportunity of subsequent erasing and falsification, and they will refrain from signing.