Reference for Zevachim 98:22

ודלמא משום דאיכא למיפרך מה לחטאת שכן מכפרת על חייבי כריתות

as there, when it is all turned white, having broken out all over him, he is clean; so here too, when it breaks out all over him,<span class="x" onmousemove="('comment',' I.e., over his whole head or beard. - Emended text (Sh. M) .');">³⁴</span> he is clean.<span class="x" onmousemove="('comment',' Thus we first learn by a hekkesh that a karahath or gabbahath in human beings covering the whole head is clean, and then that same law is applied to garments by a gezerah shawah.');">³⁵</span>

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