Ecclesiastes 9:1-6

1 For I considered all this in my heart, so that I could declare it all: that the righteous and the wise and their works are in the hand of God. People know neither love nor hatred by anything they see before them.

² All things come alike to all: one event happens to the righteous and the wicked; to the good, the clean, and the unclean; to him who sacrifices and him who does not sacrifice. As is the good, so is the sinner; he who takes an oath as he who fears an oath.

³ This is an evil in all that is done under the sun: that one thing happens to all. Truly the hearts of the sons of men are full of evil; madness is in their hearts while they live, and after that they go to the dead.

⁴ But for him who is joined to all the living there is hope, for a living dog is better than a dead lion.

⁵ For the living know that they will die; but the dead know nothing, and they have no more reward, for the memory of them is forgotten.

⁶ Also their love, their hatred, and their envy have now perished; nevermore will they have a share in anything done under the sun.

before them (v.1) — Nobody knows whether they will face good or bad in their future. It is up to God. righteous/wicked (v.2) — in their conduct toward others clean/unclean (v.2) — morally and ceremonially clean, or impure, before God

It is unclear if the one who swears an oath is someone who takes an oath before God in a positive manner, or if it refers to someone who profanely takes an oath as prohibited by the Lord in Matthew 5:34. If the latter, then he who “fears an oath” is one who is afraid to offend God by carelessly swearing to things. If the former, then he who “fears an oath” is one who is afraid of making an oath or vow to God. Because the pattern in this verse is to list the good before the bad, it would seem that “he who takes an oath” is a positive characteristic and would be referring to the man who makes solemn oaths to God and keeps them. — Grace, page 1178.

evil (v.3, first use) = something dysfunctional or very wrong

Solomon … found that there was only one great fact that could be verified, and that is, the fact of death (v.3). This supreme evil strikes all, whether good or bad, young or old, without pity. … The vicissitudes of life affect the good and the evil; and therefore the good are not exempted from the supreme calamity of death. Verse 3 would better read: “This is the greatest calamity of all, ” i.e., the fact of death; and yet in spite of this fact, men’s hearts are filled with evil and madness so long as they live. In the East a dog (v.4) is the vilest of animals and a lion the noblest. … The dead lose six factors possessed by the living (vs.5-6) viz.: knowledge, memory, love, hatred, envy, and “a portion under the sun,” that is, life. — Williams, page 446.

one thing happens to all (v.3) — death happens to all those described in verse 2.

The “evil” (that everyone good or bad, religious or irreligious, moral or immoral all die just the same regardless of their behavior) is made worse (v.3) by how the evil man (who induces himself to more and more wickedness while he lives) dies just like the righteous with no apparent penalty for his aberrant behavior. — Grace, page 1178.

hope (v.4) — the chance to change one’s eternal destiny.

An objective surveillance of the events which occur in our lives furnishes a mixture of evidence which, in the final analysis, does little to establish absolutely God’s love or hatred of an individual man. The fates and fortunes of all men seem remarkably similar. … The sinner’s freedom from divine punishment causes him to fill his heart with madness and rebellion while he lives. The vision of death as the universal obliteration breeds madness in the hearts of those who do not companion with wisdom. The Hebrew word translated madness implies a blindness to the true issues. These poor men are blinded all the days of their miserable existence. They lack the ability to see things rightly, for they have refused the profit of wisdom’s illumination. Hence, from their darkness and evil they go to death. They pass from death to death. … As long as they are joined to the living there is hope, or as … verse 4 states, a living dog is better than a dead lion. — KJV Commentary, page 749.

forgotten (v.5) — The dead have no knowledge of earthly events, no benefit from their earthly labors, and no one to remember them after they’re gone.

now (v.6) — the moment they died

perished (v.6)— Even their strong passions died when they died.

nevermore will they have a share (v.6) — The are forever cut off from everything and everyone still on earth.