Reference for Chullin 82:18

עושה מקום חוץ לגומא ושוחט ודם שותת ויורד לגומא

OR THE PASSOVER-OFFERING OR A THANK-OFFERING, THE SLAUGHTERING IS INVALID;<span class="x" onmousemove="('comment',' The sacrifices enumerated here can be vowed or offered as freewill-offerings at all times; the onlooker therefore might suppose that the slaughterer has just now consecrated the animal for the particular offering mentioned and would believe that it is permitted to slaughter a consecrated animal outside the sanctuary. For this reason the Rabbis declared the slaughtering invalid.');">⁷</span>

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