Gittin 72A

רבי יוסי היא, דאמר: מילי לא מימסרן לשליח.

It is the opinion of R' Yosei, who says: Verbal directives cannot be delegated to an agent, and there is no concern that the scribe signed the document without the husband instructing him to do so.

ואי סלקא דעתך מודה רבי יוסי באומר ״אמרו״, נפיק מינה חורבא ⁠– דזימנין דאמר להו לשנים ״אמרו לסופר ויכתוב, ולפלוני ופלוני ויחתמו״; ומשום כיסופא דסופר ⁠– חיישי ומחתמי ליה, ובעל לא אמר הכי.

And if it enters your mind to say that R' Yosei concedes in the case of one who says: Tell another to write it, a pitfall will result from it. As sometimes, it happens that one said to two people: Tell a scribe and he will write the document and tell so-and-so and so-and-so and they will sign it. And due to the shame of the scribe, who asks: Don’t you consider me a sufficiently upright person to sign the document as a witness, the agents are concerned to avoid that disgrace and they will have one of those witnesses and the scribe sign together with him, and the husband did not say to do so. This bill of divorce is invalid because it was signed contrary to the husband’s instructions, and the agents will mistakenly think it is valid.

אלא מחוורתא, רישא רבי מאיר וסיפא רבי יוסי.

The reason that this is not a concern must be because R' Yosei holds that even if the husband says to the agents: Tell the scribe to write, the bill of divorce is not valid. Rather, it is clear that the first clause of the Mishnah is in accordance with the opinion of R' Meir and the latter clause is in accordance with the opinion of R' Yosei.

רב אשי אמר: כולה רבי יוסי היא, ולא מיבעיא קאמר: לא מבעיא היכא דלא אמר ״תנו״, אלא אפילו אמר ״תנו״⁠ – לא. ולא מיבעיא היכא דלא אמר לבי תלתא, אלא אפילו אמר לבי תלתא ⁠– לא. ולא מיבעיא היכא דלא אמר ״אמרו״, אלא אפילו אמר ״אמרו״⁠ – נמי לא.

Rav Ashi said an alternative explanation of the attribution of the Mishnah: The Mishnah in its entirety is in accordance with the opinion of R' Yosei, who said that verbal directives cannot be delegated to an agent, and it is speaking utilizing the style of: It is not necessary, as follows: It is not necessary to state that the bill of divorce is not valid in a case where he did not say to the agents: Give the document to my wife; rather, even if he said to the agents: Give the bill of divorce to my wife, the document is not valid. And it is not necessary to state the halakha in a case where the husband did not say his instructions to 3 people; rather, even if he said his instructions to 3 people, no, the bill of divorce is not valid. And it is not necessary to state the halakha in a case where the husband did not say to the agents: Say my instructions to a scribe, but even if he said: Say my instructions to a scribe, the bill of divorce is also not valid.