Deuteronomy 23:12

Thou shalt have also a place without the camp
A place prepared, as the Targums of Onkelos and Jonathan, provided on purpose for the use hereafter suggested; so Ben Melech:

whither thou shalt go forth abroad;
to do the necessities of nature, which they were to do without the camp, not in any place they thought fit and most convenient, but what was appointed for that purpose.