A man who keeps his word
My answer may seem worthless but I think it would be better if you use "a man of his word" (not "a man his word"). Or would 'truthful' be appropriate?
A man of integrity.
according to ODO:
in·teg·ri·ty
noun 1. the quality of being honest and having strong moral principles; moral uprightness. "he is known to be a man of integrity" synonyms: honesty, probity, rectitude, honor, good character, principle(s), ethics, morals, righteousness, morality, virtue, decency, fairness, scrupulousness, sincerity, truthfulness, trustworthiness
The three-word term is a recognised collocation, almost a compound noun (12.4 m Google hits). The adjective 'integritous' does exist but is rarely used.
Is there a reason "honorable" doesn't suit? especially since you seem to be looking for something with that kind of connotation specifically?
The two basic definitions I seem to find mean either 1. in keeping with that standard code of conduct called honorable (as in chivalry, or actions considered honorable in a specific group) OR 2. having and keeping their own code of conduct, consistently (keeping their given word, being responsible for their own actions)
The second definition is perfectly in line with your meaning, the first might have some additional connotations depending on the context you use it in and who gets to define 'honorable' in that context.
From Dictionary.com, honorable includes
- in accordance with or characterized by principles of honor; upright: They were all honorable men.
- of high rank, dignity, or distinction; noble, illustrious, or distinguished.
- worthy of honor and high respect; estimable; creditable.
- bringing honor or credit; consistent with honor.
The first mentions an outside standard of honor, the last two deal with self-consistency and reliability.