Commentary for Eruvin 7:11
נוֹתֵן אָדָם מָעָה לְחֶנְוָנִי וּלְנַחְתּוֹם כְּדֵי שֶׁיִּזְכֶּה לוֹ עֵרוּב, דִּבְרֵי רַבִּי אֱלִיעֶזֶר. וַחֲכָמִים אוֹמְרִים, לֹא זָכוּ לוֹ מְעוֹתָיו. וּמוֹדִים בִּשְׁאָר כָּל אָדָם שֶׁזָּכוּ לוֹ מְעוֹתָיו, שֶׁאֵין מְעָרְבִין לְאָדָם אֶלָּא מִדַּעְתּוֹ. אָמַר רַבִּי יְהוּדָה, בַּמֶּה דְבָרִים אֲמוּרִים, בְּעֵרוּבֵי תְחוּמִין, אֲבָל בְּעֵרוּבֵי חֲצֵרוֹת, מְעָרְבִין לְדַעְתּוֹ וְשֶׁלֹּא לְדַעְתּוֹ, לְפִי שֶׁזָּכִין לְאָדָם שֶׁלֹּא בְּפָנָיו, וְאֵין חָבִין לְאָדָם שֶׁלֹּא בְּפָנָיו:
One may give money to a shopkeeper [who sells wine and dwells with him in the mavui] or to a baker [who sells loaves and dwells with him in the courtyard] to assign to him (a share in) the eruv [with his fellows, viz.: "If the men of the mavui come to buy wine from you for a partnership, or the men of the courtyard, to buy a loaf for the eruv, let me have a share in it."] These are the words of R. Eliezer. The sages say: His money does not acquire for him. [For money does not acquire until one pulls (the purchased object). And even if the shopkeeper provided an eruv for all the others and also assigned it to this one, it is not an eruv, for he did not intend to assign it to him as a gift, gratis, in the manner of those who assign eruvin, but that he acquire it for the money. But he does not acquire it, for money (without "pulling") does not acquire; so that he is found to have made an eruv with his money.] And they concur that with other men (i.e., not shopkeepers) his money does acquire it. [If the house-owner says to his neighbor: "Take this money and assign an eruv for me," and he went and did so, he (the house-owner) acquires the eruv. For since the (other) house-owner does not regularly sell loaves, the first intended only to make him a messenger, as if he had said: "Make an eruv for me."] For an eruv may be made for another only with his knowledge. [Therefore, in the instance of the shopkeeper, when he said to him: "Assign it to me," his intent was only to acquire it from him, and he did not depend upon him as a messenger. And money does not acquire, and there was no empowering, so that he (the shopkeeper) would be making an eruv for him without his knowledge.] R. Yehudah said: When is this so? With eruvei tchumin (Sabbath bound eruvin) [which can be a liability, for he loses on the other side (of the tchum), and he may not wish it. The halachah is in accordance with R. Yehudah.], but with courtyard eruvin, the eruv can be made with or without his knowledge. For a man may be benefitted (even) when he is not present, and he may not be made to incur a loss except when he is present.
Bartenura on Mishnah Eruvin
English Explanation of Mishnah Eruvin
The sages say: his money acquires no share for him
They agree that in the case of all other men his money may acquire [an eruv for him],
Since they do not prepare an eruv except with one’s consent.
Rabbi Judah says: To what does this apply? To Shabbat border eruvin, but in the case of courtyard eruvin they prepare an eruv with his consent and without his consent, since they confer a benefit on a person in his absence but they do not confer a disability on a person except in his presence.
This mishnah discusses one person’s ability to set up an eruv for someone else.
Section one: According to Rabbi Eliezer, a person can give a small amount of money (a ma’ah, which is a small coin) to a baker or shopkeeper in order that they will contribute from their food toward the eruv on his behalf. The coin acquires for him the food for the eruv and it is as if he is contributing directly toward the eruv.
Section two: The sages disagree because money cannot acquire movable property (things see the first chapter of Kiddushin). In order to acquire something, one must lift it up or at least pull it towards himself. Therefore, he has not acquired the food that the shopkeeper gives for the eruv. Therefore, he has not effectively contributed to the eruv.
Section three: The sages agree with Rabbi Eliezer that if he gives the money to a different person, meaning some sort of agent, and the agent buys the food from the shopkeeper or baker, this is an effective means to set up an eruv. This is effective because the person’s agent validly acquires the food from the shopkeeper or baker by actually taking it from him. Similarly, a person can ask a shopkeeper to set up an eruv on his behalf, since the shopkeeper will give the food to another person, causing the other person to acquire the food, and therefore the shopkeeper is acting as the person’s agent. The only problematic situation is if the person says to the shopkeeper that his money should acquire the eruv since money cannot effect acquisition, this type of eruv setup is invalid.
Section four: Although this section seems attached to the previous one, it is actually separate. According to the first opinion, one cannot set up an eruv without the consent of the person who will benefit from the eruv. This is true, according to this opinion, for both Shabbat border eruvin and courtyard eruvin. Rabbi Judah, on the other hand, says there is a difference between the two types of eruvin. Consent is required to set up a Shabbat border eruv for someone because there is some “disability” in this as well. Namely, if the Shabbat border eruv extends his ability to travel outside the city toward one direction, he loses a commensurate amount in the other direction. Hence, one cannot set up a Shabbat border eruv for someone without his permission. However, one only gains by having a courtyard eruv set up on his behalf and therefore, one can set up a courtyard eruv for someone without their consent.