Matthew Henry Commentary Deuteronomy 23:9-14

"When thou goest forth in camp against thine enemies, then thou shalt keep thee from every evil thing. If there be among you any man, that is not clean by reason of that which chanceth him by night, then shall he go abroad out of the camp, he shall not come within the camp: but it shall be, when evening cometh on, he shall bathe himself in water; and when the sun is down, he shall come within the camp. Thou shalt have a place also without the camp, whither thou shalt go forth abroad: and thou shalt have a paddle among thy weapons; and it shall be, when thou sittest down abroad, thou shalt dig therewith, and shalt turn back and cover that which cometh from thee: for Jehovah thy God walketh in the midst of thy camp, to deliver thee, and to give up thine enemies before thee; therefore shall thy camp be holy, that he may not see an unclean thing in thee, and turn away from thee." — Deuteronomy 23:9-14 (ASV)

The camp of the Lord must have nothing offensive in it. If this care must be taken to preserve the body clean, much more should we be careful to keep the mind pure.