Deuteronomy 23:9-14

⁹"When you go forth against your enemies and are in camp, then you shall keep yourself from every evil thing. ¹⁰"If there is among you any man who is not clean by reason of what chances to him by night, then he shall go outside the camp, he shall not come within the camp; ¹¹but when evening comes on, he shall bathe himself in water, and when the sun is down, he may come within the camp. ¹²"You shall have a place outside the camp and you shall go out to it; ¹³and you shall have a stick with your weapons; and when you sit down outside, you shall dig a hole with it, and turn back and cover up your excrement. ¹⁴Because the LORD your God walks in the midst of your camp, to save you and to give up your enemies before you, therefore your camp must be holy, that he may not see anything indecent among you, and turn away from you.