John Calvin Commentary Psalms 49:18

"Though while he lived he blessed his soul (And men praise thee, when thou doest well to thyself,)" — Psalms 49:18 (ASV)

“For he will bless his soul in his lifetime.” Various meanings have been attached to this verse. Some read, He ought to have blessed his soul during his life. Others apply the first clause of the verse to the wicked, while they refer the second to believers, who are in the habit of praising God for all his benefits. Others understand the whole verse as descriptive of believers, but without sufficient ground.

There can be little doubt that the reference is to the children of the world. In the first part of the verse, it is said that they bless their own soul as long as they live on earth. This means that they indulge and pamper themselves with earthly pleasures, giving way to the excesses of brutish intemperance, like the rich man of whom Christ spoke in the parable, who said, “Soul, you have much goods laid up for many years; take your ease, eat, drink, and be merry” (Luke 12:19).

Alternatively, it means that they seek their happiness entirely from this world, without cherishing a desire for the life that is to come. Some translate the Hebrew verb as he will do good, and read it this way: He will do good to his own soul in his lifetime. But I understand the phrase to be synonymous in its meaning with that which was used by Moses: “And it come to pass, that he bless himself in his heart” (Deuteronomy 29:19).

That is, he flatters himself as if he might despise God with impunity. The inspired writer here represents the stupidity of those who please themselves with a fallacious dream of happiness. In the latter part of the verse, the person is changed, and the devotee of pleasure is addressed directly; the prophet insinuating, by the words he uses, that the preposterous pride with which the wicked are inflamed is in part the consequence of the delusive applause of the world, which pronounces them to be happy and echoes their praises even when they gratify their most unrestrained passions.