Reference for Pesachim 126:10

בעא מיניה רב אושעיא מרבי אמי אין לו לשוחט ויש לו לאחד מבני חבורה מהו אמר ליה מי כתיב לא תשחט על חמצך (שמות לד, כה) לא תשחט על חמץ כתיב

R'Papa said: As a corollary, the priest who burns the fat [on the altar] violates a negative command, since he is subject to the general [interdict of] leaving the emurim overnight.<span class="x" onmousemove="('comment',' I.e., if he still has leaven when he burns the fat, even if none of the company has any.');">¹⁵</span> It was taught in accordance with R'Papa. He who slaughters the Passover sacrifice with leaven violates a negative command - When is that?

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