Torah Portion: Shemini
“ומפתח אהל מועד לא תצאו פן תמותו” (ויקרא י ז)
It is a negative commandment that kohanim not leave the Sanctuary while the Service is in progress, as it is written, Do not leave the entrance of the Tent of Meeting lest you die (Vayikra 10:7).
Among the roots of the mitzvah is the fundamental idea discussed earlier, which is to glorify the honor of the Holy Temple and the Services that are performed there. It is therefore proper to not walk out on such precious Service for any reason in the world. For, in truth, if the person would leave it, that would be disrespectful and their action would show that they think there is something greater than serving Hashem. Because of the seriousness of this transgression, the kohanim were warned about this under the penalty of death.
This mitzvah applies when the Holy Temple stands, to kohanim.