Does exceeding the scope of authorization invalidate the agency contract?

Primary text

The agency contract is not invalidated by transgression in the matter for which one was authorized, such as the agent wearing the garment or riding the animal he was instructed to sell. This is the primary view held by adherents of the Shafi'i school. The evidence supports this because when the agent acts, he acts with the permission of the principal, thus the action is valid, just as if he had not transgressed. Agency is a grant of permission to act which includes a trust (*amanah*). If the trust aspect is negated by transgression, the permission to act remains intact.