Leviticus 13:49
and if the mark in the fabric, leather, weave, knit, or leather article is green or red, then it is contaminated with mildew and must be shown to the priest.

Leviticus 13:51
On the seventh day the priest shall reexamine it, and if the mildew has spread in the fabric, weave, knit, or leather, then regardless of how it is used, it is a harmful mildew; the article is unclean.

Ezekiel 44:23
They are to teach My people the difference between the holy and the common, and show them how to discern between the clean and the unclean.