Ezekiel 44:23

Part of the priests’ job would be to teach the people the difference between the holy and the common, and between the unclean and the clean. The people would learn this difference as they observed the distinctions prescribed here and as the priests explained them to them (cf. Ezekiel 22:26; Leviticus 10:10-11; Leviticus 11:47; Deuteronomy 33:10).

"The priests were by their lives to be examples of separateness; their ritual holiness was intended to promote ethical holiness among the people they were called to serve. [Note: Taylor, p. 272.]

This is also the duty of believer priests today (1 Peter 1:13-16).