John Calvin Commentary Jeremiah 44:27

"Behold, I watch over them for evil, and not for good; and all the men of Judah that are in the land of Egypt shall be consumed by the sword and by the famine, until there be an end of them." — Jeremiah 44:27 (ASV)

Here he more clearly expresses what he had said in the last verse: that none of the Jews would remain alive in Egypt. He now points out the manner, because he would not cease to consume them until they completely perished and were brought to final ruin. He had said, No more shall my name be called, nor shall the Jews in Egypt swear, As Jehovah lives; and why? Because I will destroy them all, so that there will be none remaining in Egypt to pollute my name under a false pretense.

I will watch over them, he says, for evil and not for good. This way of speaking we have observed elsewhere, and we have explained why the Prophets spoke thus: because hypocrites, though they think God does not care for human affairs and imagine that he sleeps in heaven, and therefore audaciously provoke him, as if they were fugitives and their purpose was hidden from God, yet boast of God’s providence and pretend that they confidently trust in him. For this reason the Prophet answered that God indeed watched, but not for good. We then perceive the Prophet's purpose; he derided the presumption of the people, who thought that God cared for their safety. He then says that God indeed does not sleep, but that this would bring no benefit to hypocrites, for though God watches as a father to preserve his own people, yet he watches as a judge to destroy all the ungodly.