Proverbs 26:23-24

²³As if thou wouldest adorn a vessel of earth, (that is, a cheap pot made out of clay), with the dross of silver, so be swelling lips fellowshipped with a full wicked heart.

²⁴An enemy is understood by his lips, when he treateth guiles in his heart. (An enemy can be understood by his words, when he treateth deceitfulness in his heart.)