Tradition
St. Augustine
City of God
Book XX › Chapter 27
Of the Separation of the Good and the Bad, Which Proclaim the Discriminating Influence of the Last Judgment
The passage also which I formerly quoted for another purpose from this prophet refers to the last judgment, in which he says, “They shall be mine, says the Lord Almighty, in the day in which I make up my gains,” etc. When this diversity between the rewards and punishments which distinguish the righteous from the wicked shall appear under that Sun of righteousness in the brightness of life eternal—a diversity which is not discerned under this sun which shines on the vanity of this life—there shall then be such a judgment as has never before been.
Source: City of God (New Advent)