A false witness shall perish: but the man that heareth speaketh constantly.
– Proverbs 21:28
The word for perish means to go astray, or be destroyed. A false witness is a lying witness, which works all kinds of evil (Proverbs 6:19; 19:5). The second phrase is difficult and interpretations vary. The word for constantly means enduring, or perpetuity. The word for heareth means to hear intelligently, or to understand. From the contrast with the first phrase, we know a faithful witness is in view (Leviticus 5:1). In ultimate terms, truth will endure and falsehood will not last (Proverbs 12:19), and that seems the overall point of the proverb.