Parallel
Numbers 5:13
Brenton's English Septuagint · Berean Standard Bible
and [supposing] any one shall lie with her carnally, and the thing shall be hid from the eyes of her husband, and she should conceal it and be herself defiled, and there be no witness with her, and she should not be taken;
by sleeping with another man, and it is concealed from her husband and her impurity is undetected (since there is no witness against her and she was not caught in the act),