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 may put difference between holy and unholy, and between unclean and clean;
Deuteronomy 24:8
Take heed in a 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 the LORD, If you return, then will I bring you again, and you shall stand before me: and if you take forth the precious from the vile, you shall be as my mouth: let them return unto you; but return not you unto them.
Ezekiel 44:23
And they shall teach my people the difference between the holy and the common, and cause them to discern between the unclean and the clean.