What does Proverbs 12:19 mean?

This verse emphasizes that positive, truthful speech has a lasting quality. While the harm done by lies can linger (Proverbs 12:18), dishonesty tends to expose itself (Proverbs 12:13). Lies self-destruct and destroy those who make them. Truth endures because there is nothing deceptive or false about it.

In a deeper, eternal sense, words are indicators of the condition of one's heart (Matthew 15:18). Those whose lives are identified with deceit and lies are defying God. Jesus noted that "out of the abundance of the heart the mouth speaks" (Matthew 12:34). In view here is not an occasional telling of the truth or an occasional telling of a lie, but rather, prolonged practices. Believers make it a practice—a way of life—to tell the truth, and those who make a practice—a way of life—to lie demonstrate a lack of faith in God. Believers will live forever, but unbelievers will experience judgment, the second death mentioned in Revelation 20:14.

"Only a moment" in Proverbs 12:19 translates a Hebrew phrase which means the same as the English expression "blink of an eye." Judgment will fall on unbelievers swiftly, in the blinking of an eye (Proverbs 29:1).