“A worthless person, a wicked man, goes about with crooked speech …” (v12). The proverbs vividly describe the pitfalls of all kinds of sins: laziness (v10-11), bad stewardship (v2), adultery (v29), etc. People who habitually lie and “sow discord,” or stir up conflict, are considered especially dangerous, because they ruin the peace and trust of the whole community (v19). Just like adultery, lying (especially about others) has ugly consequences that ripple out through our entire network of relationships.
“For the commandment is a lamp” (v23). God doesn’t want us to stumble around in the dark; His commands show us the way to healthy relationships and a joyful life.