Probity

Probity
words are Ælflæd of Duckford's unless specified otherwise, or unless clearly dictionary quotations

Probity is integrity, but more. Probity is honesty, but in a form more related to trustworthiness. When a person has probity, it is easy for others to trust his words and to have faith in his judgment.

Buddha said [or someone said]:

Do not believe in anything simply because you have heard it. Do not believe in traditions because they have been handed down for many generations. Do not believe in anything because it is spoken and rumored by many. Do not believe in anything simply because it is found written in your religious books. Do not believe in anything merely on the authority of your teachers and elders. But after observation and analysis, when you find that anything agrees with reason, and is conducive to the good and benefit of one and all, then accept it and live up to it.

This quote has been around since the 1950's but is not documentable as is.
Still, nice whoever said/wrote it.

The "live up to it" is the hardest of all. When you find that another person *is* worthy of trust and you have discovered that on your own by your own observation and test, THEN the person has probity with you. Don't take anyone's word for the probity of another.

From Webster's Revised Unabridged Dictionary (1913) [web1913]:

Probity \Prob"i*ty\, n. [F. probit['e], fr. L. probitas, fr. probus good, proper, honest. Cf. {Prove}.]
Tried virtue or integrity; approved moral excellence; honesty; rectitude; uprightness.
``Probity of mind.'' --Pope.

Syn: {Probity}, {Integrity}.

Usage: Probity denotes unimpeachable honesty and virtue, shown especially by the performance of those obligations, called imperfect, which the laws of the state do not reach, and can not enforce. Integrity denotes a whole-hearted honesty, and especially that which excludes all injustice that might favor one's self. It has a peculiar reference to uprightness in mutual dealings, transfer of property, and the execution of trusts for others.

From WordNet: probity n : complete and confirmed integrity

Probity (from French probité, from Latin probitas, from probus: “good, honest”):

Complete and confirmed integrity; uprightness (synonyms at “honesty”) (American Heritage Dictionary) That's the definition used by Word of the Day when they featured "probity."

Virtue or integrity tested and confirmed; strict honesty (synonyms under “virtue) (Funk & Wagnall)

Moral excellence, integrity, rectitude, uprightness, conscientiousness, honesty, sincerity (Oxford English Dictionary)

ETYMOLOGY, ancient, from Indo-European roots:

Compound *pro-bhw-o-, growing well or straightforward (*bhw-o-, to grow; see bheu- in Indo-European roots). PROBABLE, PROBE, PROBITY, PROOF, PROVE; APPROVE, IMPROBITY, REPROVE, from Latin probus, upright, good, virtuous. (More, and it's related to "prowess" (way back in time) and less directly related to privy, primary, privilege, principle, prince...)