Written and Oral Torah Sealed by Covenant at Sinai

(Exodus 34:27:) "Write for yourself these words, [for according to the mouth of these words, etc.]." Rabbi Yochanan, Rabbi Yehoshua, and Rabbi Shimon say: "(I gave you) 'the words' is not written here, but rather 'according to the mouth of the words.' I gave you Written Torah and Oral Torah. If you made what is written into oral, and what is oral into written, and you exchanged them, you do not receive a reward. Why? Because I gave you Written Torah and Oral Torah, and I made a covenant with you on condition that you recite them in this way. But if you exchanged it, know that the covenant will be nullified, as it is said: 'Lest you forget the things that your eyes have seen' (Deuteronomy 4:9) — those that are written in writing; 'and lest they depart from your heart' (ibid.) — these are the oral ones."