Bava Batra 161b — the Talmud in English

It is not Jacob's,

for we know that there is no one in this country whose name is Jacob, and this is his signature.

And the Gemara raises an objection:

Perhaps he signed with his father's name,

so that the court might err and think that this is Reuven's own signature, although he customarily signs in his father's name, writing his father's name!

And the Gemara answers:

He would not abandon his own name and sign with his father's name.

They would not err in this, since a person does not customarily sign in his father's name instead of signing in his own name.

And the Gemara raises an objection:

Perhaps he made it merely as a sign,

and perhaps he was accustomed to write “Jacob” not as a name, but chose these letters as a sign!?

For Rav would draw a fish,

Rav would make the figure of a fish as a sign for his signature, and everyone knew that it was Rav's signature.

Rabbi Ḥanina would draw a palm branch,

he would draw palm branches as a sign for his signature.

Rav Ḥisda

would write the letter

samekh

from his name alone.

Rav Hoshaya

would write the letter

ayin

from his name alone.

Rava bar Rav Huna

would draw

a ship's mast,

the mast of a ship.

And the Gemara answers:

A person is not brazen enough to use his father's name as a sign.

A person does not have the audacity to use his father's name as a sign for his signature.

Mar Zutra said: Why do you need all this?

Why is it necessary to reconcile Rabbi Yirmeya bar Abba's opinion with forced explanations? It can be explained simply:

Any linked document whose witnesses do not end on one line is invalid.

All the witnesses' signatures on a linked document must begin and end at precisely the same place, one directly beneath the other. If so, there is no need to say that the witnesses sign specifically from bottom to top; whether they sign from top to bottom, from the beginning of the document toward its end, or whether they sign from bottom to top, the matter is resolved. For if they sign from top to bottom, he cannot add lines at the end of the document, since they would then be beneath the witnesses' signatures. And if they sign from bottom to top, then if he cuts off the final line, it will emerge that the first part of each witness's name is missing, and it will be evident that this is fraud.

Rabbi Yitzḥak bar Yosef said that Rabbi Yoḥanan said: All erasures,

if there are erasures in a document in a place where it is valid [for example, in a place where it is impossible that the words “valid and confirmed” were written must be verified; he should write at the end of the document

“And this is their verification”

[these are the verifications in this document], and specify the words that he corrected in place of the erasures. Otherwise, there is concern that he erased and corrected the document as he wished after the witnesses had signed.

And he must repeat the substance of the document on the final line.

He must write on the final line a summary of the document's contents, as we customarily write: “And we acquired from so-and-so son of so-and-so for so-and-so, in accordance with everything written and specified above.” It must not contain a new matter that has legal significance, such as a condition upon which the document is contingent.

And the Gemara explains:

What is the reason?