Solomon’s proverb here is such an obvious truth that it seems more like two definitions than a proverb. Of course: a truthful witness gives honest testimony, whoever speaks the truth declares what is right, and the person who will speak the truth will reveal righteousness. This is learned at a very early age.
The second half is just as easy to agree with: a false witness tells lies, a false witness speaks deceit, and the witness of falsehood reveals deceit. This also is learned at a very early age.
Sitting among some deep thought-provoking proverbs the simple verse 17 is almost comical. Who doesn’t know this? The surprising truth is many do not know themselves. They do not know when they are a truthful or a false witness. What was I yesterday? How do I define myself? Is the Holy Spirit telling me something about myself that I have been ignoring?
The Hebrew here makes the apparent future tense a continual act or habit. Paraphrased, “He who accustoms himself to speak the truth in common conversation will be an honest testimony in public judgment and therefore can be depended upon with an honest testimony all the time.” If I ask those who know me if they trust my word all the time, what would they answer?
A false witness who pours out lies is one of the six things the Lord hates (6:19). Reckless words mames souls, carving wounds that may never heal (12:18, 25:18; Psalm 57:4). A mouth of lies is an open grave (Psalm 5:9). I dismiss my words that do not conform to the truth as justifiable. Yet, God does not distinguish. Jesus said the religious leaders of his day were dead men walking because they did not accept or speak the truth (Matthew 23:47). Am I like a white-washed tomb, which looks beautiful on the outside but on the inside is full of dead men’s bones?
