John Calvin Commentary Jeremiah 36:24

"And they were not afraid, nor rent their garments, neither the king, nor any of his servants that heard all these words." — Jeremiah 36:24 (ASV)

The Prophet now connects doctrine with the narrative, for what we have until now seen would be frigid if no instruction were added. He then shows why he had related what we have read of the king’s impious obstinacy. Indeed, there is more force in a simple statement than if the Prophet had denounced the king and his counselors in high-sounding words, for he speaks here as one astonished.

They did not tear, he says, their garments, nor feared when they heard threats so dreadful. And undoubtedly, it may be justly considered the most monstrous of things that miserable men should disregard God's threats with such contempt, which they yet ought to have dreaded no less than instant destruction.

That mortals then should not be moved when God fulminates with His threats against them, but on the contrary become more hardened—this is an evidence of diabolical madness. It is therefore not without reason that the Prophet says, as one astonished, that neither the king nor his counselors feared nor tore their garments.

Now, we are taught in this passage that it is a sign of reprobation when we are not terrified when God threatens and declares that He will become our judge, and when He brings forward our sins, and also shows what we deserve. When, therefore, all those things produce no effect on us, it is a sure sign of hopeless madness. This is what the Prophet means when he says, they feared not, for his object was to show that all, as well as himself, ought to stand amazed that the king and his counselors could thus fearlessly withstand the threats of God.

As to the garments, the sign is put for the thing itself, and then a statement of a part is made for the whole:

1. To tear the garments is of no great moment unless the heart is first torn, as Joel says (Joel 2). But though hypocrites make a show of repentance by fallacious signs, yet when true and sincere repentance is discussed, the sign is put in the place of the thing signified, as in this passage: they did not tear their garments, that is, they manifested no fear. And as the tearing of garments was usually done, he says that they did not tear their garments when God, by the mouth of Jeremiah and by the hand of Baruch, fulminated against them.
2. A part is stated for the whole, because they were accustomed to put on sackcloth and to sprinkle ashes on their heads. Only garments are mentioned here, but other signs were also included.

He says, When they heard all these words; not that the king heard the whole volume, but three or four chapters were sufficient to condemn him. For there is no doubt that he was abundantly convicted, and that he threw himself into such a rage as to cut the roll and not to tear his garments, because he dreaded God’s judgment. And there is a striking alliteration in the words קרע koro, to cut, and קרא kora, to read, the first ending with ע (ayin), and the other with א (aleph). He had previously said that when Jehudi read a part of the roll, the king cut it; the one read and the other cut. And he says here that the king did not cut (it is the same word) or tear his garments. The king had before cut the roll and torn it in pieces when, on the contrary, he and the rest ought to have cut or torn their garments—and, if it were lawful, even themselves—when God terrified them with such dreadful threats.