John Gill's Exposition of the Whole Bible
Proverbs 12:19
The lip of truth shall be established for ever,.... The man that speaks truth is and will be established in his credit and reputation among men; he is uniform and all of a piece, and what he says is believed; truth, though it may be opposed, will prevail against lies and falsehood; the word of truth, the Gospel of Christ, will stand for ever; the ministers of truth and righteousness will be continued to the end of the world; Christ, who is truth itself, abides the same to day, yesterday, and for ever;
but a lying tongue [is] but for a moment; if a liar speaks truth for once, he does not continue in it long, but quickly returns to his former course; or rather the lie he tells is very short lived, it is soon discovered, and he comes into contempt and disgrace, and loses all his credit and reputation among men of honour and honesty, and is sometimes suddenly snatched away by death, as Ananias and Sapphira; all error and heresy in a short time will cease and be no more; and antichrist, whose coming is with lying wonders, the direct opposite of the lip of truth, will be brought to ruin in a moment. Aben Ezra, Kimchi, and Ben Melech, who are followed by some Christian interpreters, as Montanus, and some in Vatablus, render it, "but", or "for ever, I will cause the lying tongue to cease", or "be at rest" from speaking; as if they were the words of God, threatening to cut off the lying tongue; but Jarchi and Gersom render it "for a moment", or a very short time, as we and others do; or, "whilst one winks" f, in the twinkling of an eye; so soon is such a person removed.
f עד ארגיעה "at dum nictem", Schultens.