Leviticus 14:57 KJV

To teach when it is unclean, and when it is clean: this is the law of leprosy.
Leviticus 14:57, King James Version

In context

56 And for a rising, and for a scab, and for a bright spot:

57 To teach when it is unclean, and when it is clean: this is the law of leprosy.