He confirms what he had said by this reason, that they ran without being called, according to what we found in Jeremiah 23:21. He then repudiates these false prophets, for they spoke not from the mouth of God. But the difference was rendered very obscure and indistinct, when they pompously alleged the name of God and professed that they brought forward nothing but what they had learnt from him; yet as we have elsewhere said, no one can be deceived except willingly and knowingly; for God never leaves his faithful people destitute of the spirit of discernment, provided they offer themselves cordially and sincerely to be taught by his true and legitimate servants. And then the Jews ought to have examined all the doctrines and all the prophecies by the rule of the Law. But if the Law was difficult to be understood, they ought, as I have said, to have sought of God the spirit of wisdom and discernment. Jeremiah then did not without reason reject whatever the false prophets boasted of, for the purpose of gaining the approbation and applause of the people; for they were not sent nor approved by God. So also at this day, every one who wishes to distinguish with certainty between various doctrines, by which the world is agitated, nay, shaken, can without difficulty attain his object, provided he offers himself as a scholar to Christ, and connects the Law and the Prophets with the Gospel, and makes use of this rule to prove all doctrines; and provided in the meantime he trusts not to his own acumen, but submits himself to God and seeks of him the spirit of judgment and discrimination. It ought also to be observed, that in the same way the false prophets can be abundantly exposed when we thus shew that they are not sent by God; and we further convince them of vanity, when we prove their doctrine to be inconsistent with the Law and the Gospel. However this may be, this principle ought to be held, that none ought to be attended to, but those who can shew that they bring messages from God and are furnished with his word. We have said elsewhere, that in order that any one may be accounted as sent by God, it is necessary, first, that he should be rightly called, and secondly, that he should faithfully execute his office; for whosoever thrusts in himself without the command of God, though he may speak what is true and holy, he yet deserves not the name of a Prophet or teacher; and then vocation itself will not be sufficient, except there be faithfulness and integrity. But what Jeremiah mainly insists on here is, that those who promised the people a return in a short time did not speak from the mouth of God: They prophesy falsely, he says, in my name; how? Because I have not sent them. It follows --

For they prophesy falsely unto you in my name,.... They pretended to have the authority of God for what they said; that their prophecies and dreams were from him, and as such they delivered them in his name; though they were false ones; that they might be the better received by the people:
I have not sent them, saith the Lord; they had no mission or commission from the Lord, no warrant or authority from him; they set up themselves; and ran without being sent; and prophesied out of their own hearts what came into their heads, the fancies of their own brain, or the delusions of Satan, under whose power and influence they were; therefore sad must be the case of a people giving heed to such seducing spirits.