Reference for Bekhorot 44:4

וחכמים אומרים

But the Sages say: A se'ah is separated and eaten in a mouldy state,<span class="x" onmousemove="('comment',' From excessive dryness. Or it means, crumbled pieces less than the size of an egg. Although there is here clean and unclean food, nevertheless, so long as the former is not being made fit to receive levitical uncleanness, i.e. does not come in contact with a liquid, the mixture can be eaten in the manner set forth here.');">³</span>

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