Reference for Chullin 58:22

כל העסוקין בפרה מתחלה ועד סוף מטמאין בגדים ופוסלין אותה במלאכה אחרת

R'Zera raised this objection: All who take part in the service of the Red Cow, either at the beginning or a the end, render their garments unclean.<span class="x" onmousemove="('comment',' I.e., the garments worn by them whilst performing the service, in accordance with Num. XIX. 7, 8, and 10.');">¹⁰</span>

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