Reference for Chullin 200:13

וכי תימא קסבר

Should you, however, say that he [R'Judah] is of the opinion that nerves do not impart a flavour, so that in the case [where one ate the nerve] of an unclean animal there is only the prohibition of the nerve but not the prohibition of [eating] what is unclean;<span class="x" onmousemove="('comment',' The sciatic nerve of an unclean animal is only forbidden qua nerve and not as unclean meat, for the nerve is tasteless and hard as wood.');">¹²</span>

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