I Gave My Word: Played very, very straight indeed. As is known throughout the Worlds, the word (or debt) of an Imperial is as close to absolute as you can get. (They are sometimes, if you are prone to abuse these things, Exact Words, and since they are cautious with regard to the vicissitudes of possibility and the universe, often hedged with qualifiers – this formed, in fact, the basis of the Empire’s contract law, hence the term oath-contract, and why unlike many jurisdictions, they do not require consideration – but they will very definitely be binding and executed as given.) No mighty oaths or swearing-bys or other elaborate formulae required; a simple I Give My Word is enough for anyone.
Indeed, while not legally binding in the way that giving one’s word is, just about any promissory statement given is considered morally and ethically binding. Let those who are in the habit of speaking loosely and promising casually beware the social consequences, indeed.
Exact Words: The Imperials are, of course, sophonts of their words. It would be very bad form for one to chop logic so closely and obey the letter, and not the spirit, of an agreement.
Unless, of course, your counterparty is trying to do it to you first, or other such constrained circumstances apply (such as, say, certain kinds of diplomacy, in which a non-cooperative environment is essentially assumed), in which case, everyone’s an exquisite space-lawyer.