Reference for Zevachim 209:13

בתר דבעיא הדר פשטה מחוסר יציאה כמחוסר מעשה דמי

They themselves, however, do not defile garments;<span class="x" onmousemove="('comment',' The carcasses do not defile any garments which they touch.');">¹³</span> but they defile foodstuffs and liquids: these are the words of R'Meir.

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