מְחָק פָּסוּל וְאַף עַל פִּי שֶׁמְּקוּיָּם but a document with a reference to words written over an erasure is not valid, even if it is verified at the end of the document. At the end of a document, before the formula: Everything is confirmed and established, is written, any corrections made in the document are verified by adding to the text: On line so-and-so, such and such a word has been added, or some similar formulation. This may be done only for inserted corrections, not for erasures.
וְלֹא אָמְרוּ מְחָק פָּסוּל אֶלָּא בִּמְקוֹם שָׁרִיר וְקַיָּים וּכְשִׁיעוּר שָׁרִיר וְקַיָּים The Gemara clarifies this statement: And they said that an erasure on a document renders the document not valid only if it is in a place on the document where the declaration: Everything is confirmed and established, should have been written, and only if the erasure is the measure of space in which the declaration: Everything is confirmed and established, can be written. The only concern with erasures is that the crucial formula: Everything is confirmed and established, might have been erased, as this would allow for unlimited forgery. If the erasure is such that this formula could not possibly have been erased, the document is valid.
וּלְרַב יִרְמְיָה בַּר אַבָּא דְּאָמַר אֲחוֹרֵי הַכְּתָב וּכְנֶגֶד הַכְּתָב מִבַּחוּץ לֵיחוּשׁ דִּלְמָא כָּתֵיב מִגַּוַּאי מַאי דְּבָעֵי וּמַחְתִּים סָהֲדֵי יַתִּירֵי מֵאַבָּרַאי וְאָמַר אֲנָא לְרַבּוֹת בְּעֵדִים הוּא דַּעֲבַדִי § Rami bar Ḥama asked Rav Ḥisda: And according to Rav Yirmeya bar Abba, who says that the witnesses sign on the back of the written side, taking care that the signatures are exactly opposite the writing, on the outside let there be a concern that perhaps the party holding the document will write whatever he wants on the inside, i.e., the front of the document, adding to the text, and then have extra witnesses sign on the outside, and he will say to anyone questioning the number of witnesses being more than the minimum: I did this in order to increase the number of witnesses, the more to publicize the matters written in the document.
אֲמַר לֵיהּ מִי סָבְרַתְּ עֵדִים כְּסִדְרָן חֲתִימִי עֵדִים מִמַּטָּה לְמַעְלָה חֲתִימִי Rav Ḥisda said to him: Do you maintain that the witnesses sign in order, that is, one under the other, starting from the top of the page on the back? This is not correct; rather, the witnesses sign from bottom to top. The witnesses sign in a perpendicular direction relative to the text of the document. The first signature begins at the reverse side of the last line of the document, and it continues upward toward the first line. There is therefore no possibility of adding to the text of the document, as, if the text extended beyond the beginning of the signatures, it would be recognized as a forgery.
וְלֵיחוּשׁ דִּלְמָא מִתְרַמְיָא רֵיעוּתָיה בְּשִׁיטָה אַחֲרוֹנָה וְגָיֵיז לַיהּ לְשִׁיטָה אַחֲרוֹנָה וְגָיֵיז לֵיהּ לִרְאוּבֵן בַּהֲדֵיהּ וּמִתַּכְשַׁר בְּבֶן יַעֲקֹב עֵד דִּתְנַן בֶּן אִישׁ פְּלוֹנִי עֵד כָּשֵׁר Rami bar Ḥama continues to question the method of signature prescribed by Rav Yirmeya bar Abba: But let there be a concern that perhaps something detrimental to the holder of the document happens to appear in the final line of the document, and he excises the final line, and in doing so excises the first name of the witness on the opposite side as well. For instance, if the witness’s name is Reuven, son of Ya’akov, he will excise Reuven along with the final line of the document, and the document will be rendered valid with the remaining part of the signature: “Son of Ya’akov, witness.” As we learned in a mishna (Gittin 87b): If one signs: Son of so-and-so, witness, without mentioning his own name, the document is valid.
דִּכְתִיב רְאוּבֵן בֶּן בְּחַד דָּרָא וְיַעֲקֹב עֵד עִלָּוֵויהּ The Gemara answers: It is a case where it is written “Reuven, son of” on one line, i.e., opposite the final line of the document, and “Ya’akov, witness,” above it, beginning from the penultimate line of the document and continuing upward in a perpendicular manner. That is, a tied document is valid only if the witnesses sign in this manner. In this case, if the final line of the document is excised, all that will remain of the signature will be: “Ya’akov, witness.”
וְלִיחוֹשׁ דִּלְמָא גָּיֵיז לֵיהּ לִרְאוּבֵן בֶּן וּמִתַּכְשַׁר בְּיַעֲקֹב עֵד דִּתְנַן אִישׁ פְּלוֹנִי עֵד כָּשֵׁר Rami bar Ḥama continues to ask: But let there be a concern that perhaps he will excise the final line of the document, along with the words “Reuven, son of,” and the document will be rendered valid with the remaining part of the signature: “Ya’akov, witness.” As we learned in a mishna (Gittin 87b): If someone signs just: So-and-so, witness, the document is valid.
דְּלָא כְּתִיב עֵד The Gemara answers: It is a case where the word witness is not written after the witnesses’ names. That is, a tied document is valid only if the word witness does not appear after the signatures. It is only in such a case that the document cannot be materially changed by excising the final line without rendering the witnesses’ names disqualified.
וְאִיבָּעֵית אֵימָא לְעוֹלָם דִּכְתִב עֵד דְּיָדְעִינַן בַּהּ דְּהָא חֲתִימוּת יְדָא And if you wish, say instead that actually the witness did write “witness” after his signature, and the case is one where we know for a fact that this signature, which consists of the words “Ya’akov, witness,”