Adam Clarke on Psalms 39:5

My days as a handbreadth - My life is but a span; σπιθαμη του βιου.

And mine age is as nothing - כאין keein, as if at were not before thee. All time is swallowed up in thy eternity.

Verily every man at his best state - כל אדם נצב col adam nitstab, "every man that exists, is vanity." All his projects, plans, schemes, etc., soon come to nothing. His body also moulders with the dust, and shortly passes both from the sight and remembrance of men.