The Written Torah and the Oral Torah May Not Trade Places

"Write for yourself these words, for by the mouth of [these words]" (Exodus 34:27). Rabbi Eleazar said: the Torah is mostly in writing and a minority by mouth, as it is said, "I would write for him the great things of My Torah" (Hosea 8:12). Rabbi Yochanan said: it is mostly by mouth, as it is said, "for by the mouth of these words." And the other one too — is it not written, "I would write the great things"? That is asked as an astonished question. And the other one too — is it not written, "for by the mouth of these words"? That is because they [the Oral teachings] are difficult, and one is not able to state them fully in writing. Rabbi Yehudah bar Nachmani, the interpreter [meturgeman] of Resh Lakish, expounded: it is written, "Write for yourself these words," and it is written, "for by the mouth of these words." How can both stand? Words that are in writing you are not permitted to recite by mouth, and words that are by mouth you are not permitted to recite in writing. The school of Rabbi Yishmael taught: "these" — these you write, but you do not write laws [halakhot]. Rabbi Yochanan said: the Holy One, blessed be He, made a covenant with Israel only for the sake of the words that are by mouth, as it is said, "for by the mouth of these words I have made a covenant with you and with Israel." They said: perhaps a new matter is different, for indeed Rabbi Yochanan and Resh Lakish would study a book of aggadah on the Sabbath, and they expounded thus: "It is a time to act for the LORD; they have voided Your Torah" (Psalms 119:126) — better that one letter of the Torah be uprooted than that the Torah be forgotten from Israel. Great is circumcision, for it is weighed against all the commandments of the Torah, as it is said, "for by the mouth of these words I have made a covenant with you."