And not spare continually to slay the nation? - They are running from conquest to conquest; burning, slaying, sacking, and slaughtering. Like the fishermen, who throw cast after cast while any fish are to be caught, so Nebuchadnezzar is destroying one nation after another. This last sentence explains the allegory of the net.
Shall they therefore empty their net, and not spare continually to slay the nations? - The prophet, like Isaiah Isaiah 18:4-5, stands at the very last point, before the fury and desire of the enemy was fulfilled. People, like fish, were gathered together for a prey; he who had taken them was rejoicing and exulting beforehand in his booty; his portion and meat were the choice of the earth; the prophet leeks on, as it were, and beholds the net full; there is but one step more; “Shall he empty it? Shall he then devour those whom he has caught? and so cast his emptied net again unceasingly, pitilessly, to slay the nations?” This question he answers in the next chapter - A Deliverer will come!