“…He shall then take off his garments and put on other garments, and he shall remove the ashes to outside the camp…” – Vayikra 6:4
וּפָשַׁט אֶת בְּגָדָיו וְלָבַשׁ בְּגָדִים אֲחֵרִים וְהוֹצִיא אֶת הַדֶּשֶׁן אֶל מִחוּץ לַמַּחֲנֶה – ויקרא ו, ד
One of the tasks in the Mishkan was to clear the ashes from atop the Altar and dispose of them outside the camp; in the times of the Beis Hamikdash, they were disposed outside the city of Jerusalem.
This task was not an actual part of the Temple service. Moreover, the kohen doing this task was required to change into garments of lesser value than those regularly worn by the kohanim, as clearing the ash might cause his clothing to become soiled. Nevertheless, no kohen ever hesitated to do this job (see Rambam, Temidim Umusafim 2:14).
This serves as an important lesson to us all. The Jewish people are called “a kingdom of kohanim” (Shemos 19:6), and our responsibilities toward each other mirror the services performed by the kohanim in the Temple.One might imagine, that he can make a distinction between the duties “within the camp” and those “outside the camp.” He will devote himself exclusively to addressing the spiritual needs of those within a Torah environment, but the task of reaching out to Jews who are “outside the camp” of Torah observance he will leave to others. It is a necessary and important task, he admits, but others are more suitable for the job.
The clearing of ash from the Altar teaches us that this approach is incorrect. The same kohanim who took part in the service within the Temple would happily change into lesser garments and take the ashes outside the camp, despite this task not being an actual part of the service. Likewise, the true “kohen,” even if he is normally within the confines of a holy Torah environment, must readily change into “lesser garments”—engaging each of his fellow Jews on their level, in the hope that he will eventually draw them near to Torah and mitzvah observance.
—Likkutei Sichos vol. 37, p. 6, ff. 33