Deuteronomy 23:10-13

10“If there is any man among you who is [ceremonially] unclean because of nocturnal emission, then he must go outside the camp; he shall not come back to the camp.

11But when evening comes, he shall bathe in water, and at sundown he may return to the camp.

12“You shall also have a place outside the camp to which you may go,

13and you shall have a spade among your tools, and when you [prepare to] sit down outside [to relieve yourself], you shall dig a hole with it and shall turn and cover up your waste.