"To take vengeance upon the nations. What is this vengeance? The Holy One, blessed be He, said: 'I will avenge what was done to Israel,' as it says, 'Vengeance for the blood of His servants is spilled' (Psalm 79:10). And vengeance is not taken by a person, as it says, 'Vengeance is Mine, and recompense' (Deuteronomy 32:35).
It also says, 'Rejoice, O nations, with His people' (Deuteronomy 32:43), and 'Thus says the Lord: "To whom I will be avenged"' (Nahum 1:2). All these acts of vengeance are in the hands of the Holy One, blessed be He, against the wicked. Therefore, it is said to take vengeance upon the nations. Lest you say that this applies to all people, the Holy One, blessed be He, said that it applies only to the kings of the gentiles, as it says, 'To bind their kings' (Psalm 149:8).
Why did these kings come against Israel? As it says, 'Why do the nations rage?' (Psalm 2:1). Therefore, it is said to bind their kings. The Holy One, blessed be He, said, 'Blessed is the one who will repay you for your deeds' (Psalm 137:8).
And what was their repayment to Israel? 'The eyes of Zedekiah were blinded' (2 Kings 25:7). And I will do the same to them, as it says, 'And their nobles shall be bound in chains of iron' (Psalm 149:8). The Holy One, blessed be He, said, 'Do they think that I have forgotten what they have done?'
It is written before Me, as it says, 'For the day is coming, burning like a furnace' (Malachi 3:19), and 'They shall go forth and look upon the corpses of the men' (Isaiah 66:24). To execute upon them the judgment that is written. And what is the judgment that is written? 'Let sinners be consumed from the earth' (Psalm 104:35). Therefore, it is said to execute upon them the judgment that is written."