Deuteronomy 23:10-11

23:10 If there is someone among you who is impure because of some nocturnal emission, ¹  he must leave the camp; he may not reenter it immediately. 23:11 When evening arrives he must wash himself with water and then at sunset he may reenter the camp.

[23:10]  ¹ tn Heb “nocturnal happening.” The Hebrew term קָרֶה (qareh) merely means “to happen” so the phrase here is euphemistic (a “night happening”) for some kind of bodily emission such as excrement or semen. Such otherwise normal physical functions rendered one ritually unclean whether accidental or not. See Lev 15:16-18; 22:4.