Albert Barnes Commentary Ecclesiastes 9:5-6

"For the living know that they shall die: but the dead know not anything, neither have they any more a reward; for the memory of them is forgotten. As well their love, as their hatred and their envy, is perished long ago; neither have they any more a portion for ever in anything that is done under the sun." — Ecclesiastes 9:5-6 (ASV)

See (Ecclesiastes 8:12), note; (Ecclesiastes 8:14), note. The living are conscious that there is a future before them, but the dead are unconscious; they earn nothing, receive nothing, even the memory of them soon disappears. They are no longer excited by the passions that belong to people in this life; their share in its activity has ceased. Solomon here describes what he sees, not what he believes. There is no reference here to the fact or the mode of the existence of the soul in another world, which are matters of faith.

The last clause of (Ecclesiastes 9:6) indicates that the writer confines his observations on the dead to their portion in, or relation to, this world.

(Ecclesiastes 9:6) Now - Rather: “long ago.”