(83) You may well ask why the Torah did not state clearly what it means, instead of our needing the oral Torah for clarification? After all, wording such as this only encourages those who doubt that Torah is of Divine origin and who deny the authority of the Rabbis to interpret it!
(84) The answer is found in the statement that the written Torah has seventy facets (Bamidbar Rabbah 13,15). This is similar to יין wine which numerically adds up to seventy. This means that the halachic norm of any מצוה listed in the Torah, is based on the oral tradition. Were this not so, the written Torah could not be subject to a variety of interpretations which reveal many other concerns of Torah.