Reference for Chullin 137:28

מבלבל זרעיה

or perhaps we only permit the product of two prohibited substances but not of three?<span class="x" onmousemove="('comment',' Namely, that in a foetus taken out alive from the womb of its slaughtered dam after it had protruded a limb, there are inherent three prohibitions, viz., that of the blood, of the forbidden fat, and of the protruded limb.');">¹⁷</span>

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