Jeremiah 29:9

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.