Reference for Bekhorot 121:31

איתמר האומר לשלוחו

whereas if he called the eleventh the tenth, it is not sacred.<span class="x" onmousemove="('comment',' Since it is a peace-offering, he loses the breast and the right shoulder which must be given to the priest, and therefore the sender can say: 'I did not send you to cause me a loss'. We therefore maintain that the sending was void.');">²⁰</span>

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