John Calvin Commentary Jeremiah 46:6

"Let not the swift flee away, nor the mighty man escape; in the north by the river Euphrates have they stumbled and fallen." — Jeremiah 46:6 (ASV)

He first says that they would gain power, but he speaks soon after of their fall. This might seem like a repetition, unless one considers that the beginning of the verse may also be read affirmatively: The swift shall not flee, etc. But as the particle אל, al, is often used in a prohibitory sense, the verse can clearly be explained as spoken by God. Thus, it can be read in connection with the previous verse: Let not the swift flee, nor the brave escape. For God here declares authoritatively that speed and courage would be of no use to the Egyptians, because the swiftest would be taken by their enemies, and the bravest would fall.

He says, In the land of the north, on the bank of the river. We know that Babylon, Assyria, Chaldea, and those countries were north of Judea. Whenever the Prophets speak of the Babylonians, they call them Northlanders. Egypt, however, was to the south, as is clear from many parts of Scripture. But as the Prophet here speaks of the Egyptians, he rightly describes Chaldea as being to the north. Then he says, On the bank of the river Euphrates they shall stumble, or fall. The meaning is that the outcome of war is in God's power, so that he would tear in pieces and lay prostrate or scatter the Egyptians, however well equipped they might be and however much they trusted in their own strength.

We must also observe that whatever provisions men procure for themselves to protect their safety, they are worthless when God opposes them. The Prophet indeed mentions only two things. However, he means that even if men excel in many things and possess many endowments, they must still perish when that is God’s will: flight cannot save the swift, nor strength the valiant.