Augustine of Hippo

"For in death there is no one that is mindful of You" [Psalm 6:5]. He knows too that now is the time for turning unto God: for when this life shall have passed away, there remains but a retribution of our deserts. "But in hell who shall confess to You?" [Luke xvi] That rich man, of whom the Lord speaks, who saw Lazarus in rest, but bewailed himself in torments, confessed in hell, yea so as to wish even to have his brethren warned, that they might keep themselves from sin, because of the punishment which is not believed to be in hell. …

Exposition on Psalm 6 ↗

Thomas Aquinas

Then when he says "For," he shows the imminent danger. And first, the danger of present death, namely natural death. Second, of eternal damnation, from which there is no return. Hence, "For there is none in death," that is, after death, "who is mindful of you," namely by thinking of your goodness, if he was not mindful of it in life. And this is so because the rational soul does not have flexibility of choice after death. Eccl. …

Exposition on the Psalms of David ↗