If the making of a contract means anything it must be evaluated by some higher principle. Therefore, it has very much to do with ethics and morality. You can see this clearly in John Locke.
You and I agree or make a contract on something and I immediately act against it or just ignore it. What can you say? "You broke the contract" -- you are saying I acted immorally or unethical or just plain lied. Is a lie nothing? then telling the Truth is nothing.