One who perceives the truth has a force, a beauty of character, which creates a favorable impression that opens doors and accomplishes things. Would we not rather loan money to a person we know works hard and pays his debts than a person with poor work habits who defaults on his obligations?
A wise person is one who recognizes truth, understands that he must meet his obligations and submits to it. This process produces a good witness whether the obligation to truth is met verbally or behaviorally. If a person will not do this, he deceives himself that he can somehow "get away with it," and his witness and name will demonstrate his poor character.
This principle holds true in every area of life upon which a name is built, whether in marriage, child training, employment, or health. Many run from the truth about themselves. Nothing destroys a reputation quicker and more permanently than for a person to be known as a liar or a hypocrite.
Therefore, the ninth commandment covers not only making a false witness about another or an event with the tongue, but also not bearing false witness about God by our conduct.