אורח חיים שס״טOrach Chayim 369

Se’if 1א׳

הַנּוֹתֵן מָעוֹת לְנַחְתּוֹם וְאָמַר לוֹ: אִם יָבוֹאוּ בְּנֵי הֶחָצֵר לִקְנוֹת מִמְּךָ כִּכָּר לְעֵרוּב זְכֵה לִי בָּעֵרוּב שֶׁיְּהֵא לִי חֵלֶק עִמָּהֶם בִּשְׁבִיל מָעָה זוֹ, אֵינוֹ עֵרוּב אֲפִלּוּ עֵרֵב הַחֶנְוָנִי (לְכָל הָאֲחֵרִים) וְזָכָה גַּם לְזֶה עִמָּהֶם; אֲבָל אִם אָמַר לוֹ: עֲרֵב לִי, קָנָה עֵרוּב. וַאֲפִלּוּ אִם אָמַר: זְכֵה לִי, אִם נָתַן לוֹ כְּלִי בְּתוֹרַת קִנְיָן שֶׁיִּקְנֶה לוֹ בּוֹ, קָנָה עֵרוּב. וְכֵן אִם זִכָּה לוֹ הַנַּחְתּוֹם עַל יְדֵי אַחֵר, אוֹ שֶׁקָּנָה בְּמָעָה שֶׁנָּתַן לוֹ לֶחֶם מִן הַשּׁוּק, קָנָה עֵרוּב. וְאִם נָתַן לוֹ מָעָה לְבַעַל הַבַּיִת וְאָמַר לוֹ: זְכֵה לִי בָּעֵרוּב, קָנָה עֵרוּב.

One who gives money to a baker and says to him: "If the residents of the courtyard come to buy a loaf from you for the eruv (the loaf set aside to join separate households into one for the Sabbath), acquire a share in the eruv for me, so that I shall have a portion with them for this maah (a small silver coin)" — it is not an eruv, even if the shopkeeper made the eruv for all the others and granted a share to this man too along with them. But if he said to him, "Make the eruv for me", he has acquired the eruv. And even if he said, "Acquire it for me", if he gave him a vessel by way of a formal act of acquisition, that he should acquire it for him with it, he has acquired the eruv. And likewise if the baker granted it to him through another person, or bought bread in the market with the maah that he gave him, he has acquired the eruv. And if he gave the maah to the householder and said to him, "Acquire the eruv for me", he has acquired the eruv.