Reference for Zevachim 31:16

ורבי אלעזר מאי טעמא לא אמר מומן המקדש לא יצא אמר לך מי כתיב הא אחר שלא יצא חילל

ONEN. How do we know it? - Because it is written, Neither shall he go out of the Sanctuary, and he shall not profane [the Sanctuary of his God]:<span class="x" onmousemove="('comment',' Lev. XXI, 12. This refers to a High Priest when an onen: he must remain in the sanctuary (for sacrificing) . and is assured that he will not profane, i.e. , disqualify the sacrifices at which he officiates.');">²¹</span>

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