Reference for Chullin 279:5

לא מכלל דאיכא אסורה

from which we may deduce that there is [a zippor] that is unclean! - No, we may deduce that there is [a zippor] that is forbidden.<span class="x" onmousemove="('comment',' Although it is a clean bird.');">⁴</span>

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