Eruvin 18A

להרחיק כל שהוא, ובלבד שירבה בפסין. רבי יהודה אומר: עד בית סאתים.

to distance the boards from the well and expand the enclosed area by any amount, i.e., as much as one wishes, provided that he increases the number of upright boards between the double posts. R' Yehuda says: The partitioned area may be expanded up to an area of two beit se’a, which is an area of 5,000 square cubits.

אמרו לו: לא אמרו בית סאתים אלא לגנה ולקרפף, אבל אם היה דיר או סהר או מוקצה או חצר ⁠— אפילו בית חמשת כורין, אפילו בית עשרה כורין מותר. ומותר להרחיק כל שהוא, ובלבד שירבה בפסין.

The Rabbis said to him: They only spoke of an area of two beit se’a with regard to a garden or an enclosure used for storing wood, scrap, and the like [karpef]. But if it was a pen [dir], or a stable [sahar], or a backyard, or a courtyard in front of the house, even if it had an area of 5 beit kor or even 10 beit kor, it is permitted. And it is permitted to distance the boards and expand the enclosed area by any amount, provided that one increases the upright boards between the double posts.

גמ׳ לימא מתניתין דלא כחנניא, דתניא: עושין פסין לבור וחבלין לשיירא. וחנניא אומר: חבלין לבור, אבל לא פסין.

Talmud: The Talmud suggests: Let us say that the Mishnah is not in accordance with the opinion of Ḥananya, as it was taught in a baraita: One may arrange upright boards around a water cistern and ropes around a caravan. Ḥananya disagrees and says: One may set up ropes for a cistern, but not upright boards.

אפילו תימא חנניא בור לחוד באר לחוד.

The Talmud rejects this suggestion: Even if you say that the Mishnah was taught in accordance with the opinion of Ḥananya, a cistern of collected rain water has a discrete law, as the water will eventually be consumed and the upright boards will become unnecessary; and a well of spring water has a discrete law, as the water is constantly renewed and the upright boards will remain useful.