Reference for Chullin 256:49

בין ר"ע לר' יוסי הגלילי מאי איכא בינייהו

but if he first intended it as food and then cut it off, it is unclean.<span class="x" onmousemove="('comment',' Inasmuch as this morsel was regarded as a foodstuff whilst still joined to the limb, it has always borne uncleanness; for when joined to the limb it bore the graver uncleanness (which can render men and vessels unclean) , and when separated from it it thereby loses the graver uncleanness but bears the lighter uncleanness (which can render unclean only foodstuffs and liquids) because of its contact with the limb.');">²⁰</span>

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