(1) The obligor is responsible for intent and negligence if a higher or lower degree of liability neither is laid down nor is to be inferred from the other subject matter of the obligation, in particular the giving of a guarantee or the assumption of a procurement risk. The provisions of sections 827 and 828 apply accordingly.
(2) Anyone acts negligently who fails to exercise the care required in business dealings.
(3) The obligor may not be released in advance from liability for intent.