Suppose Ahmad cannot present a receipt, and the center’s payment record is unavailable. “No receipt has been shown” does not by itself establish “No payment was made.” The reasoning lesson is that an unproven premise cannot support a certain conclusion.
The sound response states that the permission, exception, and restoration condition are clear, but Ahmad’s outcome depends on checking the facts. This is not an instance of mujmal wording: the rules are intelligible; the uncertainty concerns an external fact.