A false witness will not go unpunished, and he who speaks lies will not escape.
This proverb teaches us the danger in telling lies—especially about other people. In a legal setting, lying about others while under oath is called perjury and is a punishable crime. One can pay a steep fine or even experience jail time for being a false witness in a courtroom. Read Deuteronomy 19:16-21 to see how seriously perjury was to be taken in ancient Israel.
There are other physical penalties that come from lying about others. One major penalty will be that people will not trust a habitual liar. If you make lying—especially about other people— a way of life, you will not be trusted by people and will eventually be isolated.
The greatest danger of lying about others (or anything) is that it breaks the Ninth Commandment (Exodus 20:16).
In all situations: Tell the truth!
To learn more about the importance of being a truth-teller, not a liar, read “Ninth Commandment: You Shall Not Bear False Witness” and “Lying vs. Telling the Truth.”