Reference for Bekhorot 109:21

לא מצטרפין

- Rather said R'Hiyya B'Abba in the name of R'Johanan: The following is the reason of R'Meir: Scripture says: And the Jordan was the border of it on the east side;<span class="x" onmousemove="('comment',' Josh. XVIII, 20.');">¹⁴</span>

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