“But keep yourselves from the things set apart, or you will be set apart for destruction. If you take any of those things you will set apart the camp of Israel for destruction and bring disaster on it. For all the silver and gold, and the articles of bronze and iron, are dedicated to the Lord and must go into the Lord's treasury.” Joshua 6:18-19 HCSB
There is an old saying, “One bad apple spoils the whole bunch,” meaning that one bad person can ruin those around him. This saying comes from the fact that as fruit ripens it produces a gaseous hormone called ethylene, which is a ripening agent. The riper the fruit, the more ethylene it produces causing the other fruits around it to ripen faster. One apple can push all the fruit around it to ripen and eventually rot. It actually does take just one single apple to start a domino effect that ruins the rest of the bunch.
It was tempting for the Israelites to keep some of the goods that they found as they plundered the city of Jericho, but they were warned that they must leave those things that God said to destroy and they must not take anything of value because it was to go into the Lord's treasury. There was no temple but the items taken from the ruined city were probably stored near the temporary tabernacle. If just one person kept just one item it would mark the whole camp of Israel for destruction.
Challenge: Those with whom you select to spend time on a regular basis will impact your life. I have found from experience that it seems the bad always affects the good rather than the good influencing the bad. Be careful who you select as your friends. Know that it is important to follow God's instructions exactly and not partially.