Charles Ellicott Commentary Psalms 39:5

"Behold, thou hast made my days [as] handbreadths; And my life-time is as nothing before thee: Surely every man at his best estate is altogether vanity. Selah" — Psalms 39:5 (ASV)

Handbreadth. —Better, some spans long. The plural without the article has this indefinite sense.

My age. —Literally, duration. (See Psalms 17:14.) The Septuagint and Vulgate have “substance.”

Before you. —Since in God’s sight one day is as a thousand years, and a thousand years as one day. “If nature is below any perception of time, God, at the other extremity of being, is above it. God includes time without being affected by it, and time includes nature, which is unaware of it. He transcends it so completely, and his works are so profoundly subject to it, that he must be indifferent to its passing. But we stand at an intermediate point and bear an affinity with both extremes” (J. Martineau, Hours of Thought).

Truly every man ... —Better, nothing but breath is every man at his best. (Literally, though standing firm.) Compare.

“Reason thus with life—
If I lose you, I lose a thing
That none but fools would keep; a breath you are.
SHAKESPEARE: Measure for Measure.