One who falsely claims that a thief stole collateral - the obligation to pay fines for that false claim only once the false claim is proven. Which leads into a discussion of "agreeing to part" of a claim. The discussion is based on the biblical words, "ki hu zeh," which the Gemara explains needs rephrasing. Which is a dramatic statement for us to learn. Also, a review/introduction of the 4 shomerim (guardians, custodians).