What does Proverbs 4:24 mean?

As Jesus pointed out in Luke 6:45, there is a close connection between what is in the heart and what comes out of the mouth. After urging his son to guard his heart (Proverbs 4:23), Solomon tells him to put crooked speech and devious talk far from him. The term translated "crooked" here is the same as used in Proverbs 2:15. It carries the idea of someone who speaks in a manipulative or immoral manner. The same basic idea is repeated here, with a condemnation of speech which is "off-color," either in intent or in form.

Corrupt and foul talk betray an evil heart. Christians are commanded to put aside falsehood, angry words, corrupt talk, bitter words, slander, malice, and obscene talk (Ephesians 4:25–31; Colossians 3:8). The apostle James writes about the power of the tongue and says it is "set on fire by hell" (James 3:6), and he points out the incongruity of using the tongue to bless and curse (James 3:9–10). He writes in verse 10: "My brothers, these things ought not to be so."

A person may argue that words are just words, and therefore there is nothing wrong with any particular term or combination of syllables. However, that reasoning does not stand up to the indictment Scripture levels against corrupt and foul speech. Whether one feels the physical sounds matter or not, the intent of the heart matters a great deal—making it clear that controlling one's tongue is more than a mere suggestion.