“Excellent speech is not fitting.” “Excellent” is the Hebrew word yether (#03499 יֶ֫תֶר), and here it refers to excellence of speech (Waltke; Proverbs). A godless fool (Ps. 14:1) may speak very well, but what he says will lead many people to destruction.
“godless person.” The Hebrew noun translated “godless person” is nabal (#05036 נָבָל), the term for the godless fool [See Appendix 9, “Fool & Foolish”]. Many godless people are well educated and sound very eloquent and knowledgeable when they speak, but they are leading people down the path of destruction. God’s people must compare what anyone says to the Word of God, no matter how well spoken. Beyond that, godly people must look at the fruit of a person’s life to determine the truth of their character and what they are saying.