Reference for Bava Metzia 54:2
ת"ש אף השמלה היתה בכלל כל אלו ולמה יצאת להקיש אליה ולומר לך מה שמלה מיוחדת שיש לה סימנין ויש לה תובעין חייב להכריז אף כל דבר שיש לו סימנין ויש לו תובעין חייב להכריז תנא תובעין אצטריכא ליה סימנין כדי נסבא
should you say that they are Biblically [valid], we return it; but if only by Rabbinical law the Rabbis enacted this measure for civil matters only, not for ritual prohibitions?<span class="x" onmousemove="('comment',' It is a general principle that the Rabbis could freely enact measures affecting civil matters, since they had the power to abrogate individual rights of property under certain conditions. But they could not nullify ritual prohibitions. Hence, if identification marks are Scripturally valid, the divorce is returned to the messenger, who proceeds to divorce the woman therewith. But if they have no Scriptural force, the Rabbis could not institute a measure to free her from her marriage bonds which was not sanctioned by the Bible. ');"><sup>2</sup></span>