29 Is not my word like as a fire? saith the LORD; and like a hammer that breaketh the rock in pieces?
29. An non ut sit sermo meus quasi ignis (hoc est, an non sermo meus tanquam ignis) dicit Jehova? Et tanquam malleus conterens saxum (vel, rupem.)
He confirms what he said of the chaff and the wheat, but in different words. It was a fit comparison when Jeremiah compared God's word to wheat, and the figments of men to chaff. But as the Jews, through their ingratitude, rendered the word of God ineffectual, so it did not become to them a spiritual support, the Prophet says that it would become like a fire and like a hammer,  as though he had said, that though the Jews were void of judgment, as they had become hardened in their wickedness, yet the word of God could not be rendered void, or at least its power could not be taken away; for as Paul says,
"If it is not the odor of life unto life, it is the odor of death unto death to those who perish," (2 Corinthians 2:16)
and so also the same Apostle says in another place, that God's servants had vengeance in their power, for they bear the spiritual sword, in order to cast down every height that exalteth itself against Christ; but he adds,
"After the obedience" of the faithful "had been completed." (2 Corinthians 10:6)
The first and as it were the natural use of God's word is to bring salvation to men; and hence it is called food; but it turns into poison to the reprobate: and this is the reason for so great a diversity.
He said, first, that God's word was wheat, because souls are nourished by it unto a celestial life; and nothing can be more delightful than this comparison. But now he declares it to be fire and a hammer There is in these terms some appearance of contradiction; but there is a distinction to be made as to the hearers, for they who reverently embrace the word of God, as it becomes them, and with genuine docility of faith, find it to be food to them; but the ungodly, as they are unworthy of such a benefit, find it to be far otherwise. For the word which is in itself life-giving, is changed into fire, which consumes and devours them; and also it becomes a hammer to break, to tear them in pieces, and to destroy them.
The import of the whole is, that God's word ever retains its own dignity; for if it happens to be despised by men, it cannot yet be deprived of its vigor and efficacy; if it be not wholesome for food, it will be like fire or like a hammer. Then these two comparisons belong to the wicked, for God's word has another sense when called fire with reference to the faithful, even because it dries up and consumes the lusts of the flesh, as silver and gold are purified by fire. Hence the word of God is properly and fitly called fire, even with regard to the faithful; but not a devouring but a refining fire. But when it comes to the reprobate, it must necessarily destroy them, for they receive not the grace that it offers to them. It may also be called a hammer, for it subdues the depraved affections of the flesh and such as are opposed to God even in the elect; but it does not break the elect, for they suffer themselves to be subdued by it.
But this hammer is said to break the stone or the rock because the reprobate will not hear to be corrected; they must, therefore, be necessarily broken and destroyed. For this reason Paul also, while speaking of the refractory, says,
"Let him who is ignorant be ignorant."
For by these words he means that they will at last find how great is the hardness of that word with which they dare to contend through the perverseness of their heart. But that passage which I have before quoted well explains what is here said by Jeremiah, even that truth in itself is wholesome, but that it turns into an odor of death unto death to those who perish. (2 Corinthians 2:16.) Paul, indeed, speaks of the Gospel, but this may be also applied to the Law. It now follows, —
 The particle kh at the beginning of this verse, rendered ut by Calvin, seems to be without meaning. It is omitted by the Vulg., and rendered "behold" by the Sept. and Syr., as though it was chnh. Venema regarded it either as a noun, burning, from kvh, to burn, or a misprint for kch, strength, vigor, power. The last is adopted by Blayney, and approved by Horsley, and is countenanced by the Targ., "Are not all my words strong as fire?" Blayney's version is, -- Is not the power of my word like fire? This is the most probable meaning; though there is no different reading, yet the difference between the two letters is very small. -- Ed.