He told them to fear and serve the Lord, and Him alone and he told them to charge their clans to put away anything that would prevent them from worshipping God!
Like the Israelites we ALL have little idols that we need to rid our lives of in order to fully worship and serve the Creator! Jealousies, prejudices, money, material possessions...even our family and church activities can become an idol in our heart if it takes the place of our full and undivided devotion to the One who created us for fellowship and service to Him!
Joshua's legacy of service to God should remind, challenge and convict each of us that no less than total and complete devotion to God should be the standard by which all of us who name the name of Christ should live!