The question of how oral tradition becomes binding is an old one, and the Talmud answers it with a scene in Solomon's court. Rav Yehudah, reporting in the name of Shmuel, taught that when Solomon gave the traditional rules for the washing of hands and the other ceremonies the force of law, a bat kol — a heavenly voice — went out into the world.

First it quoted the book Solomon himself had written: "My son, if your heart be wise, my heart shall rejoice, even mine" (Proverbs 23:15). Then it said again, "My son, be wise, and make my heart glad, that I may answer him who reproaches me" (Proverbs 27:11).

Hear the logic the sages are drawing out. The written Torah and the oral Torah are not rivals. When Solomon stood up and ratified a custom the elders had practiced for generations, the heavens themselves rejoiced, because the wisdom of the sages is the echo of the wisdom of God. The hand that washes before the meal is continuous with the Sinai that commanded the meal in the first place.

(From the 1901 Hebraic Literature anthology, drawing on Shabbat 14b.)