Reference for Eruvin 185:10

אלא התם לאו היינו טעמא דכל ד"א לגבי כרם עבודת הכרם לגבי גדר כיון דלא מזדרען אפקורי מפקר להו דביני ביני אי איכא ד' חשיבן ואי לא לא חשיבן

it must be assumed that the reason there<span class="x" onmousemove="('comment',' Why no seed may be sown if the distance between the vineyard and the wall is less than twelve cubits.');">²⁵</span> is<span class="x" onmousemove="('comment',' Lit., 'but is not there this the reason'.');">²⁶</span> that all the space to the extent of four cubits that adjoins the vineyard is allotted for the tillage of th vineyard, and a similar space that adjoins the wall, since it cannot be sown,<span class="x" onmousemove="('comment',' The sowing of seed near a wall undermining its foundations (cf. B.B. 19a) .');">²⁷</span> is renounced<span class="x" onmousemove="('comment',' By its owner, as useless for cultivation.');">²⁸</span>

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