When the army of Israel would fight against their enemies, the Lord wanted them to make sure that they did not let anything unclean enter into their camp,
“When the army goes out against your enemies, then keep yourself from every wicked thing. If there is any man among you who becomes unclean by some occurrence in the night, then he shall go outside the camp; he shall not come inside the camp. But it shall be, when evening comes, that he shall wash with water; and when the sun sets, he may come into the camp” (Deuteronomy 23:9-11).
They were to keep the camp clean spiritually, and next year we will look at the next three verses in which He told them to keep the camp clean physically.
When we are outdoors, those are good things for Christians to keep in mind.