Reference for Bava Batra 214:8

דקתני סיפא חציה בדרום אני מוכר לך משמנין ביניהן ונוטל חציה בדרום ואמאי משמנין ביניהן והא חציה בדרום אמר ליה אלא לדמי ה"נ לדמי:

SPACE FOR THE WALL<span class="x" onmousemove="('comment',' Round half the field. ');">²⁴</span> [AND] FOR THE BIGGER AND SMALLER TRENCH.<span class="x" onmousemove="('comment',' Which is dug round the wall. A smaller trench is made between the wall and the bigger trench. ');">²⁵</span> AND WHAT IS [THE WIDTH OF] THE BIGGER TRENCH? SIX HANDBREADTHS;<span class="x" onmousemove="('comment',' Along the entire length of the field. ');">²⁶</span> AND [THAT OF] THE SMALLER ONE, THREE.<span class="x" onmousemove="('comment',' Along the entire length of the field. ');">²⁶</span>

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