John Calvin Commentary Psalms 21:10

"Their fruit wilt thou destroy from the earth, And their seed from among the children of men." — Psalms 21:10 (ASV)

Thou shalt destroy their fruit from the earth. David amplifies the greatness of God’s wrath from the fact that it will extend even to the children of the wicked. It is a doctrine common enough in Scripture that God not only inflicts punishment upon the first originators of wickedness but also makes it overflow even to their children.

And yet, when he thus pursues his vengeance to the third and fourth generation, he cannot be said to involve the innocent with the guilty indiscriminately. As the seed of the ungodly, whom he has deprived of his grace, are accursed, and as all are by nature children of wrath, devoted to everlasting destruction, he is no less just in exercising his severity towards the children than towards the fathers.

Who can bring any charge against him if he withholds from those who are unworthy of it the grace that he communicates to his own children? In both ways he shows how dear and precious to him is the kingdom of Christ:

1. In extending his mercy to the children of the righteous even to a thousand generations.
2. In causing his wrath to rest upon the reprobate, even to the third and fourth generation.