The sages defended Rav Saphra for his devotion to Oral Torah over Scripture, and in doing so they staked out one of Judaism's most startling claims. Tradition, they argued, is not the junior partner of the written text. It is the older sibling.
Tractate Soferim (chapter 15) compared Scripture to water, the Mishnah to wine, and the Gemara to mulled wine — the fuller the fermentation, the richer the cup. Another metaphor: Scripture is salt, Mishnah is pepper, Gemara is spice. The written Torah nourishes. The oral Torah flavors.
Chagigah 10a goes further. Commenting on Zechariah 8:10 — neither was there any peace to him that went out or came in — Rav declared that anyone who abandons a matter of halachah for a matter of mere Scripture will never find peace. Shmuel extended the rule to anyone who trades the Talmud for the Mishnah. Rabbi Yochanan capped it: even trading the Babylonian Talmud for the Jerusalem Talmud earns you the same restlessness.
The Jerusalem Talmud tells of Rabbi Tarfon who recited the Shema according to the school of Shammai while on the road, and nearly fell to bandits. It would have served you right, a colleague told him. You ignored the rule of Hillel. Rabbi Yochanan spelled out the principle: The words of the scribes are more highly valued than the words of the Law. To breach the rabbinic fence around Torah, he said, is like the verse in Ecclesiastes 10:8 — he who breaks down a hedge, a serpent shall bite him.
Rabbi Chanina pushed further still: The words of the elders are more important than the words of the prophets. A prophet needs signs and wonders to be trusted (Deuteronomy 13:2). An elder needs no credentials — Deuteronomy 17:11 already commands, According to the decision which they may say unto thee shalt thou do.
The king, the rabbis said, sends two ambassadors. One carries a signed letter; one carries only his face. The prophet needs the letter. The elder is the letter.