2 They, then, whose shepherd is death, seem to flourish for a time, and the righteous to labour: but why? Because it is yet night. What means, it is night? The merits of the righteous appear not, and the felicity of the unrighteous has, as it were, a name. So long as it is winter, grass appears more verdant than a tree. For grass flourishes through the winter, a tree is as it were dry through the winter: when in summer time the sun has come forth with greater heat, the tree, which seemed dry through the winter, is bursting with leaves, and puts forth fruits, but the grass withers: you will see the honour of the tree, the grass is dried.
So also now the righteous labour, before that summer comes. There is life in the root, it does not yet appear in the branches. But our root is love. And what says the Apostle? That we ought to have our root above, in order that life may be our shepherd, because our dwelling ought not to quit heaven, because in this earth we ought to walk as if dead; so that living above, below we may be dead; not so as that being dead above, we may live below....Our labour shall appear in the morning, and there shall be fruit in the morning: so that they that now labour shall hereafter reign, and they that now boast them and are proud, shall hereafter be brought under. For what follows? “Like sheep laid in hell, death is their shepherd; and the righteous shall reign over them in the morning.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)