John Gill Commentary Jeremiah 38:4

"Then the princes said unto the king, Let this man, we pray thee, be put to death; forasmuch as he weakeneth the hands of the men of war that remain in this city, and the hands of all the people, in speaking such words unto them: for this man seeketh not the welfare of this people, but the hurt." — Jeremiah 38:4 (ASV)

Therefore the princes said to the king

The four princes mentioned in (Jeremiah 38:1), having heard what Jeremiah said to the people, laid the case before the king, and addressed him upon it in the following manner:

we beseech you, let this man be put to death; or, "let this man now be put to death," as the Targum.

They speak very disrespectfully of the prophet, calling him "this man"; and with great authority to the king, and not in a submissive supplicating way, as we render it; the king, being in distress, was in their hands; he stood in fear of them, and could do nothing against their will and pleasure; and they urge that he might die instantly; they were for taking away his life at once.

The reason they give follows:

for thus he weakens the hands of the men of war that remain in this city, and the hands of all the people, in speaking such words to them;

This means he dispirited the soldiers who were set for the defence of the city, such of them as were left, who were not taken off by the sword, famine, or pestilence; since, if what Jeremiah said was true, all attempts to defend it must be in vain; and the people be without any hope of being delivered out of the hands of the enemy:

for this man seeks not the welfare of this people, but the hurt;

than which nothing was more false; for the prophet foreseeing that their lives were in danger, through the sword, famine, or pestilence, by continuing in the city, advised them to go out of it, and surrender to the Chaldeans, whereby they would be preserved.