A faithful witness will not lie: but (e) a false witness will utter lies.
(e) For the maintenance of his own ambition, and not for God's glory, as Simon Magus.

A faithful witness will not lie,.... For that would be contrary to his character as faithful; and as he will not witness to a falsehood upon oath in a court of judicature, so neither will he tell a lie in common conversation. This may be applied to Gospel ministers, who are witnesses of Christ; the Gospel they preach is a testimony concerning him, and they bear a faithful witness to the truth; nor will they, knowingly and willingly, deliver out a falsehood, or a doctrinal lie, since "no lie is of the truth", 1-John 2:21; the character of a faithful witness is given to Christ, Revelation 1:5; who is a "witness" of his father's love and grace, of his mind and will, and of the doctrines of the Gospel relating to himself, and the method of salvation by him; and he is "faithful" to him that appointed him; nor can he nor will he lie, for he is "truth" itself;
but a false witness will utter lies; or "blow" (e) them out, and spread them abroad in great plenty; he will not stick to tell them, and, having no conscience, will utter them as fast as he can, with all boldness and confidence; for one that fears not to bear testimony to a falsehood upon oath, will not scruple to lie in common talk. Or the words, "nay" be rendered, "he that uttereth lies will be a false witness"; he that accustoms himself to lying, in his conversation with men in private company, will become a false witness upon occasion in a public court of judicature: such an one is not to be depended on; lesser sins lead to greater, lying to perjury. So false teachers, and the followers of the man of sin, speak lies in hypocrisy, doctrinal ones, which they are given up to believe; and such as do so are false witnesses, deceivers, and antichrist.
(e) "efflabit", Montanus; "efflat", Junius & Tremellius, Piscator.

A conscientious witness will not dare to represent anything otherwise than according to his knowledge.

A faithful witness, &c.--one tested to be such.
utter lies--or, "breathe out lies"--that is, habitually lies (Proverbs 6:19; compare Acts 9:1). Or the sense is, that habitual truthfulness, or lying, will be evinced in witness-bearing.

Striking if also accidental is the frequency of the א and ב in Proverbs 14:4. This is continued in Proverbs 14:5, where the collector gives two proverbs, the first of which commences with a word beginning with א, and the second with one beginning with ב:
5 A faithful witness does not speak untruth;
But a lying witness breathes out falsehoods.
The right vocalization and sequence of the accents is בּקּשׁ לץ חכמה (ק with Tsere and the servile Mahpach, חכמה with Munach, because the following Athnach-word has not two syllables before the tone). As in 5a עד אמוּנים, so in 5b עד שׁקר is the subject. Different is the relation of subject and predicate in the second line of the parallel proverbs, Proverbs 14:25, Proverbs 19:5. With 5a cf. ציר אמוּנים, Proverbs 13:17; and regarding יפיח (one who breathes out), vid., at Proverbs 6:19; Proverbs 12:17.