Reference for Zevachim 28:6

ולא והאמר ר' זירא אמר רב שחיטת פרה בזר פסולה ואמר רב עלה אלעזר וחוקה כתיב בה

Said Abaye to them: But slaughtering is a service which cannot be dispensed with, and yet it is valid [when done] by a zar? - Slaughtering is not a service, he replied.<span class="x" onmousemove="('comment',' Rashi: Since it may be done by all who are otherwise unfit to perform the sacrificial service.');">²</span>

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