Leviticus 14:57
to teach when it is unclean, and when it is clean. This is the law of leprosy.
Leviticus 10:10
and that you are to make a distinction between the holy and the common, and between the unclean and the clean;
Deuteronomy 24:8
Take heed in the plague of leprosy, that you observe diligently, and do according to all that the priests the Levites shall teach you: as I commanded them, so you shall observe to do.
Jeremiah 15:19
Therefore thus says Yahweh, If you return, then will I bring you again, that you may stand before me; and if you take forth the precious from the vile, you shall be as my mouth: they shall return to you, but you shall not return to them.
Ezekiel 44:23
They shall teach my people the difference between the holy and the common, and cause them to discern between the unclean and the clean.