Reference for Keritot 8:51

(ויקרא יא, כט) וזה לכם הטמא לימד על דם השרץ והשרץ שמצטרפין זה עם זה

since the law applies in respect of uncleanness, it applies also in respect of eating; but in the case of a snake, since it does not apply in respec of defilement,it does not apply also in respect of eating; therefore he<span class="x" onmousemove="('comment',' Viz., Rabina.');">³⁰</span>

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