עירובין ב׳Eruvin 2

Mishnah 1א׳

עוֹשִׂין פַּסִּין לַבֵּירָאוֹת אַרְבָּעָה דְיוּמְדִין, נִרְאִין כִּשְׁמֹנָה, דִּבְרֵי רַבִּי יְהוּדָה. רַבִּי מֵאִיר אוֹמֵר, שְׁמֹנָה, נִרְאִין כִּשְׁנֵים עָשָׂר, אַרְבָּעָה דְיוּמְדִין וְאַרְבָּעָה פְשׁוּטִין. גָּבְהָן עֲשָׂרָה טְפָחִים, וְרָחְבָּן שִׁשָּׁה, וְעָבְיָן כָּל שֶׁהוּא, וּבֵינֵיהֶן כִּמְלֹא שְׁתֵּי רְבָקוֹת שֶׁל שָׁלֹשׁ שָׁלֹשׁ בָּקָר, דִּבְרֵי רַבִּי מֵאִיר. רַבִּי יְהוּדָה אוֹמֵר, שֶׁל אַרְבַּע אַרְבַּע, קְשׁוּרוֹת וְלֹא מֻתָּרוֹת, אַחַת נִכְנֶסֶת וְאַחַת יוֹצֵאת:

Boards are placed (upright) around wells [in the public domain. For the wells are private domain, being ten tefachim deep, so that it is not permitted to draw water from them and take it out to the public domain. Therefore, boards are arranged to form an enclosure around the well as a private domain. He can then draw water from the well and place it there, and bring in his beast entirely or its head and most of its body and water it] — four dioamudin, giving the appearance of eight (boards). ["dioamudin" - "two amudin" (boards), each one of these four (corner-pieces) giving the appearance of two boards ("dio," Greek for "two"). When he sticks one of the corner-pieces in the southwest corner, one wall extends to the east and the other to the north; the second in the northwest corner — one wall to the east, and the other, to the south. So that when he places all four on all four sides, each side has two cubits of wall, cubit facing cubit and a space in between.] These are the words of R. Yehudah. R. Meir says: Eight (boards), giving the appearance of twelve — four dioamudin and four plain boards, (each board) ten tefachim high, six tefachim (= 1 cubit) wide, any thickness, and between them ,the distance of two teams (revakoth) of three (heads of) cattle. These are the words of R. Meir. [("four plain boards":) a one-cubit board on each side in the middle. When there are ten cubits or less between the boards of these four corner-pieces, R. Meir concurs that plain boards are not needed. And when there are more than thirteen and a third cubits between them, R. Yehudah concurs that plain boards are required. They differ only (in respect to a distance of) from ten to thirteen and a third cubits, R. Meir requiring plain boards and R. Yehudah not requiring them. The halachah is in accordance with R. Yehudah. ("two revakoth of three (heads of) cattle":) For the width of each (head of) cattle is one and two-thirds cubits — so that the width of six (heads of) cattle is found to be ten cubits, this being the permitted distance between one board and the other according to R. Meir, a greater distance requiring the addition of plain boards. ("revakoth:") as in (I Samuel 28:24): "egel (a calf) marbek."] R. Yehudah says: (Two teams) of four (heads of) cattle [thirteen and a third cubits], tied and not free [So that it not be thought that "as if tied," but not literally "tied," is intended, it is stated "and not free" — for greater stringency, to reduce the space between them], one [team] entering and another leaving, [in which instance there is more space than for two leaving or two entering — for greater lenity, less constriction being required.]

Mishnah 2ב׳

מֻתָּר לְהַקְרִיב לַבְּאֵר, וּבִלְבַד שֶׁתְּהֵא פָרָה רֹאשָׁהּ וְרֻבָּהּ בִּפְנִים וְשׁוֹתָה. מֻתָּר לְהַרְחִיק כָּל שֶׁהוּא, וּבִלְבַד שֶׁיַּרְבֶּה בְּפַסִּין:

It is permitted to place [the boards] closer to the well [and to form a small enclosure], so long as [from the edge of the well until the boards there are two cubits (the length of the head and most of the body of the cow), so that] the head and most of the body be within when it drinks, [but not less, lest he follow his cow and take the pail outside the enclosure.] It is permitted to place (the boards) farther, any distance, [to make the enclosure as large as he wishes], so long as he adds boards. [For the farther the distance from the well, the greater the space between the boards. He, therefore, must add boards so that the distance between board and board or board and dioamud be no greater than thirteen and a third cubits, as per R. Yehudah, whose ruling is followed.]