⭐ The chain — Moses received, and handed onקִבֵּל

Avot 1:1. "Moses received Torah from Sinai and handed it on to Joshua; Joshua to the elders; the elders to the prophets; and the prophets handed it on to the Men of the Great Assembly."

⭐⭐⭐ The verb is קִבֵּל — kibbel, "he received", and it is the root the word Kabbalah comes from. Kabbalah does not mean "secret". It means that which was received. This entire app is named for a family of that verb.

Read the sentence as a piece of engineering and it is doing something specific: it puts the Oral Torah at Sinai alongside the written one, and then makes its authority depend on an unbroken sequence of named human beings rather than on a document. Each link receives and hands on. Nobody in the chain is the author.

⭐⭐ Which is why the chain is quoted at the head of a tractate about character rather than about law. What is being transmitted is a way of holding a thing, and the tractate goes on to say so: raise many students, be deliberate in judgment, make a fence around the Torah.

⚠ And it is a claim, not a chronicle. The chain is a rabbinic account of rabbinic authority, written by the people at the end of it. Saying so does not dispose of it — every tradition's account of its own legitimacy is written from inside — but the reader is entitled to know which end of the chain is holding the pen.