Leviticus 14:57

To teach when it is unclean and when it is clean To direct the priest when to pronounce a person or house clean or unclean. Upon the whole, we may see in these laws the religious care we ought to take of ourselves to keep our minds from the dominion of all sinful affections and dispositions, which are both their disease and their defilement, that we may be fit for the service of God. We ought also to avoid all bad company, and, as much as may be, coming within the danger of being affected by it. Touch not the unclean thing, saith the Lord, and I will receive you.