Reference for Zevachim 111:9

בשלמא אין שוחטין בעינא כנגד הפתח וליכא אלא אין חייבין אמאי

[No:] as for [saying] you may not slaughter, it is well, [the reason being that] it [slaughtering] must be opposite the door, which it is not [in these chambers]. But why [should you learn] 'and they do not involve culpability'? - Yet on your view, [consider: when you say,] you may not slaughter, are we not discussing a case where the shechitah is opposite the entrance,<span class="x" onmousemove="('comment',' I.e., that the door of this chamber faces that of the knives' recess, so that when both are open it is technically 'at the door of the test of meeting', and yet you may not slaughter there.');">¹⁰</span>

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