Kiddushin 59A

ומאי שנא התם דקתני ״האומר לשלוחו״?

and what is different there, in the previous chapter (50a), that the tanna teaches: With regard to one who says to his agent, go and betroth a certain woman for me in such and such a place, and he went and betrothed her in a different place, she is not betrothed? Why does the Mishnah there label him an agent, and here it labels him simply another?

הכא רבותא קא משמע לן, והתם רבותא קא משמע לן. הכא רבותא קא משמע לן: דאי תנא ״שלוחו״ הוה אמינא: שלוחו הוא דהוי רמאי, דסמכה דעתיה, סבר: עבד לי שליחותי, אבל חבירו, דלא סמכה דעתיה, אימא לא ליהוי רמאי.

The Talmud answers: Here the Mishnah teaches us a novel element and there it teaches us a novel element, through its use of these terms. The Talmud elaborates: The Mishnah here teaches us a novel element, as had it taught: His agent, I would say that it is his agent who is considered a scoundrel in that case, as one who sends an agent relies upon him, thinking: He will perform my agency for me, since he was sent for that purpose. But with regard to the use of the term: Another, who was not appointed and upon whom he does not rely, as he is not his agent, you might say that he should not be considered a scoundrel.

התם רבותא קא משמע לן: דאי תנא: ״האומר לחבירו״ הוה אמינא: חבירו הוא דכי קדשה במקום אחר אינה מקודשת, דסבר: לא טרח, אבל שלוחו דטרח אימא: מראה מקום הוא לו, קא משמע לן.

Similarly, the Mishnah there teaches us a novel element, as had it taught: One who says to another, I would say that it is in the case of another that she is not betrothed if he betrothed her in a different place, as he thinks that this person would not go to the trouble of looking for her elsewhere, and therefore he authorized him to betroth the woman only in that particular place. But with regard to his agent, who is assumed to take special trouble to fulfill his agency, you might say he is merely showing him the place where she is likely to be found, and she is betrothed in any case. The Mishnah therefore teaches us that even when he appointed an agent she is not betrothed if he does not find her in the place the putative husband specified.