Calvin on Jeremiah 6:16

The Prophet teaches us here that the fault of the people could not be extenuated as though they had sinned through ignorance; for they had been warned more than necessary by God. The same sentiment is found in Isaiah,
“This is your rest; but they would not hear.” (Isaiah 28:12.)
But our Prophet more at large condemns the Jews; for God had commanded them to stand in the ways, to look and to inquire respecting all the old paths. He uses a similitude: and we ought not to doubt respecting the way, since it has been shewn to us by the mouth of God. But the impiety of the people is exposed and reproved, because they did not so much as open their eyes, when God shewed them the way and allowed them a free choice: for he introduces God here, not strictly as one who commands, but as one who shews so much indulgence, that the people were free to choose the way they approved and thought best. When God deals so kindly with men, and so condescendingly sets before them what is useful and expedient, it is the basest ingratitude to reject such kindness on God’s part.
We now then understand the Prophet’s design in saying, that God had commanded them to stand in the ways and to consider what was best to be done. Consider, he says, and ye shall find rest, that is, that ye may find rest (for the copulative here denotes the end) to your souls. Here the Prophet means, that it remained only with the Jews to secure prosperity and a quiet state; for if they had obeyed the counsel of God, rest would have been provided for them: in short, he means, that they were miserable through their own willfulness; for God had set before them the prospect of a happy condition, but this favor had been despised by them, and wantonly despised, as these words intimate, And they said, We will not walk in it
We see that the people’s perverseness is here discovered; because they might have otherwise objected and said, that they had been deceived, and that if they had been in time warned, they would have obeyed good and wise counsels. In order to cut off this handle, Jeremiah says, that they from deliberate wickedness had rejected the rest offered them by God: they have said, We will not walk in it. This resolution deafly shews that they obstinately remained in their sins; so that the rest, which was within their reach, was not chosen by them.
This passage contains a valuable truth, — that faith ever brings us peace with God, and that not only because it leads us to acquiesce in God’s mercy, and thus, as Paul teaches us, (Romans 5:1,) produces this as its perpetual fruit; but because the will of God alone is sufficient to appease our minds. Whosoever then embraces from the heart the truth as coming from God, is at peace; for God never suffers his own people to fluctuate while they recumb on him, but shews to them how great stability belongs to his truth. If it was so under the Law and the Prophets, as we have seen from Isaiah, how much more shall we obtain rest under Christ, provided we submit, to his word; for he has himself promised it, “Come unto me all ye who labor and are heavy laden, and I will refresh you.” And ye shall find rest, he says here, to your souls. This passage then serves to commend this celestial truth, that it avails to pacify consciences, so that there is no perplexity nor doubt.