Deu 23:12 “Also you shall have a place outside the camp, where you may go out;
Deu 23:13 and you shall have an implement among your equipment, and when you sit down outside, you shall dig with it and turn and cover your refuse.
Deu 23:14 For the LORD your God walks in the midst of your camp, to deliver you and give your enemies over to you; therefore your camp shall be holy, that He may see no unclean thing among you, and turn away from you.

In this verse, Moses commands the Israelites to cover up their excrement because God walks in the camp and might see it.