Reference for Zevachim 26:20

לימא כתנאי דתני חדא טבילת אצבע מפגלת בחטאת ותניא אידך לא מפגלת ולא מתפגלת מאי לאו תנאי היא

But since you cannot dispense with placing it [in the utensil],<span class="x" onmousemove="('comment',' I.e., it is a necessary part of the service.');">²¹</span> you must say that it is an important service;<span class="x" onmousemove="('comment',' It is a definite service in that an illegitimate intention thereat effects piggul.');">²²</span>

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