Ps 49:19

“"Thy mouth hath abounded in malice, and thy tongue hath embraced deceit." Of the malevolence and deceit, brethren, of certain men he speaketh, who by adulation, though they know what they hear to be evil, yet lest they offend those from whom they hear, not only by not reproving but by holding their peace do consent. Too little is it, that they do not say, Thou hast done evil: but they even say, Thou hast done even well: and they know it to be evil: but their mouth aboundeth in malice, and their tongue embraceth deceit. Deceit is a sort of guile in words, of uttering one thing, thinking another. He saith not, thy tongue hath committed deceit or perpetrated deceit, but in order to point out to thee a kind of pleasure taken in the very evil doing, He hath said, "Hath embraced." It is too little that thou doest it, thou art delighted too; thou praisest openly, thou laughest to thyself. Thou dost push to destruction a man heedlessly putting forth his faults, and knowing not whether they be faults: thou that knowest it to be a fault, sayest not, "Whither art thou rushing?" If thou wert to see him heedlessly walk in the dark, where thou knewest a well to be, and wert to hold thy peace, of what sort wouldest thou be? wouldest thou not be set down for an enemy of his life? And yet if he were to fall into a well, not in soul but in body he would die. He doth fall headlong into his vices, he doth expose before thee his evil doings: thou knowest them to be evil, and praisest and laughest to thyself. Oh that at length he were to be turned to God at whom thou laughest, and whom thou wouldest not reprove, and that he were to say, "Let them be confounded that say to me, Well, well."”

“"Your mouth." Here he treats of the sin of the mouth, which is aggravated in two ways. First, from circumstances. Second, from the condition of persons, at "Sitting." Concerning the first he does two things. First, he sets forth the aggravating conditions, namely frequency. Another is deceit. Frequency: because if someone occasionally commits some sin, it is in some way tolerable. Or if from a slip of the tongue he says something disordered, it is more easily borne. Jas. 3: "If anyone does not offend in word, he is a perfect man." But if someone fills his mouth with curses, then it proceeds from his own malice; for from the abundance of the heart the mouth speaks, Mt. 12. Ps. 13: "Whose mouth is full of cursing," etc. The sin of the tongue is also aggravated by deceit or fraud. Jer. 9: "Their tongue is a wounding arrow; it has spoken deceit." And therefore he says, "And your tongue contrived deceits," that is, composed them and, as it were, as a teacher arranged deceits so that his words might be pleasing. Prov. 12: "A witness who is hasty contrives words of falsehood."”