Reference for Chullin 59:20

וכי תימא בעי העמדה והערכה והתנן

This is right if you were to say that the term shechitah applies to the entire process of the slaughtering from beginning to end, for then the paschal lamb is rendered invalid at the beginning of the slaughtering,<span class="x" onmousemove="('comment',' For although it is not slaughtered under the specific name of the paschal lamb it is nevertheless considered as such, and inasmuch as the first act of the slaughtering renders it invalid, since it is not being slaughtered at the proper time, no guilt is incurred.');">¹⁴</span>

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