Psalms 144:4

Man is like to vanity - אדם להבל דמה Adam lahebel damah, literally, Adam is like to Abel, exposed to the same miseries, accidents, and murderers; for in millions of cases the hands of brothers are lifted up to shed the blood of brothers. What are wars but fratricide in the great human family?

His days are as a shadow - The life of Abel was promissory of much blessedness; but it afforded merely the shadow of happiness. He was pure and holy, beloved of his parents, and beloved of God; but, becoming the object of his brother's envy, his life became a sacrifice to his piety.

The idea of Job is, that there is no substance, nothing that is permanent. A shadow moves on gently and silently, and is soon gone. It leaves no trace of its being, and returns no more. They who have watched the beautiful shadow of a cloud on a landscape, and have seen how rapidly it passes ever meadows and fields of grain, and rolls up the mountain side and disappears, will have a vivid conception of this figure. How gently yet how rapidly it moves. How soon it is gone. How void of impression is its course. Who can track its way; who can reach it? So man moves on. Soon he is gone; he leaves no trace of his being, and returns no more.

Psalm 144:4Man is like to vanity - See the notes at Psalm 39:5-6; Psalm 62:9. The idea here is, that man can be compared only with that which is utterly vain - which is emptiness - which is nothing.

His days are as a shadow that passeth away - See the notes at Psalm 102:11 : "My days are like a shadow that declineth." The idea is essentially the same. It is, that as a shadow has no substance, and that as it moves along constantly as the sun declines, until it vanishes altogether, so man has nothing substantial or permanent, and so he is constantly moving off and will soon wholly disappear.