Siman 369

The Rambam wrote in chapter 6, law 20: "A person may give a ma'ah to a homeowner so that he may purchase bread for him and establish an eruv for him with it. However, if he gave it to a shopkeeper or to a baker and said to him, 'Acquire for me with this ma'ah'—it is not an eruv. But if he said to him, 'Establish an eruv for me with this ma'ah'—he may purchase bread with it and establish an eruv for him. And if he gave him a vessel and says to him, 'Give me food for this and acquire it for me'—he may take food and establish an eruv for him with it." Thus far his words, and this is in the Gemara (81b). And the explanation of the matters is that when he gave a ma'ah to a homeowner to purchase bread for him for an eruv—he is his agent to establish the eruv, and a person's agent is like himself. But when he gave it to a shopkeeper or to a baker and said to him, 'Acquire for me'—he did not make him an agent but rather purchased bread from him, and since he did not perform a meshikhah, it is not his. But if he said to him, 'Establish an eruv for me'—he made him an agent, and similarly by means of a vessel—it is a kinyan sudar, and the bread is acquired for him by means of a kinyan. But if so, there is no difference between a homeowner and a shopkeeper or baker, for even to a homeowner if he says to him 'Acquire for me' it would not be effective, and to a shopkeeper or baker 'Establish an eruv for me' is also effective; and if so, the Rambam should have distinguished in the phrasing, and not between a homeowner and a shopkeeper or baker.

And in truth, the Tur and the Shulchan Aruch wrote that regarding a homeowner it is effective, even if he said "acquire for me," because it is not the way of a homeowner to sell bread. Therefore, even with "acquire for me" - his intention was not by way of sale, but by way of agency, see there; however, for the Rambam it is difficult. And it appears to me that the Rambam also holds this way, but he stated the common manner of the matter, for regarding a shopkeeper and a baker it is common to say "acquire for me," meaning from your bread which stands for sale. But to a homeowner, how could he say to him "acquire for me," for he does not sell his bread, rather he requests of him to buy on his behalf, and the language of "acquire for me" is not applicable, but rather he requests of him to take bread for him.

Behold, the Rambam wrote this law regarding eruvei techumin, see there. And we could say that regarding eruvei chatzerot and shitufi mevaot where there are many people, and one said to a baker or a shopkeeper, "acquire for me with this ma'ah," and he acquired for everyone from his own—it is an eruv. For just as he acquired for everyone from his own, he also acquired for this person from his own. But the Tur wrote that even in such a case it is not effective; for even though he acquired for everyone from his own, nevertheless, since he took a ma'ah from him, his intention was by way of sale and not by way of acquisition, and he did not purchase, see there, and this is the approach of Rashi, see there. And the Tosafot there wrote further, that even if the baker intended to acquire for him from his own, it is not effective, since he gave the ma'ah and intended only that he should purchase bread for him, and the purchase is nothing, see there. And the Rosh rejected this, for since his desire is for the eruv, why would he not be satisfied in such a case? And the Tur and the Shulchan Aruch ruled according to the opinion of the Rosh. And the reasoning of the Tosafot is also understandable, for it is more pleasing to him to perform the mitzvah with his own money and not that another should acquire it for him (Taz, subsection 4). And the Rosh holds that certainly one could say this reasoning, but since with his own money he cannot acquire without meshikhah, it is obvious that it is better for him that there be an eruv and that it not be with his own money, than that he should have no eruv at all. (See Magen Avraham, subsection 1, who raised a difficulty from Choshen Mishpat siman 199, that wine for kiddush is acquired with money alone because it is a matter of a mitzvah. And why should one not also acquire with money alone for an eruv? See there. And in truth, we cited there in Choshen Mishpat section 5 that there are those who cast doubt on this, see there. However, even without this it works out well, for in truth Rabbi Eliezer and the Sages disagreed in the Mishnah; for Rabbi Eliezer holds that for the sake of the mitzvah of eruv one acquires with money alone. And the Sages disagree with him and hold that this is not such a great mitzvah that for its sake we should nullify the enactment of the Sages who enacted meshikhah, for in what way is the enactment of eruv stronger than the enactment of meshikhah? And they did not nullify this enactment except for a Torah matter, such as during the four periods where the joy of the festival is from the Torah, and similarly kiddush is essentially from the Torah, and reflect on this.)