New Revised Standard Version
Even those who live many years should rejoice in them all; yet let them remember that the days of darkness will be many. All that comes is vanity.

Contemporary English Version
Even if you have a very long life, you should try to enjoy each day, because darkness will come and will last a long time. Nothing makes sense.

New American Bible
However many years mortals may live, let them, as they enjoy them all, remember that the days of darkness will be many. All that is to come is vanity.

Douay-Rheims Bible
If a man live many years, and have rejoiced in them all, he must remember the darksome time, and the many days: which when they shall come, the things past shall be accused of vanity.

If a man live many years, and have rejoiced in them all, he must remember the darksome time, and the many days: which when they shall come, the things past shall be accused of vanity.

if a man

Ecclesiastes 6:6 Although he lived two thousand years, and hath not enjoyed good things: do not all make haste to one place?

Ecclesiastes 8:12 But though a sinner do evil a hundred times, and by patience be borne withal, I know from thence that it shall be well with them that fear God, who dread his face.

rejoice

Ecclesiastes 3:12,13 And I have known that there was no better thing than to rejoice, and to do well in this life. . . .

Ecclesiastes 5:18-20 This therefore hath seemed good to me, that a man should eat and drink, and enjoy the fruit of his labour, wherewith he hath laboured under the sun, all the days of his life, which God hath given him: and this is his portion. . . .

Ecclesiastes 8:15 Therefore I commended mirth, because there was no good for a man under the sun, but to eat, and drink, and be merry, and that he should take nothing else with him of his labour in the days of his life, which God hath given him under the sun.

yet

Ecclesiastes 7:14 In the good day enjoy good things, and beware beforehand of the evil day: for God hath made both the one and the other, that man may not find against him any just complaint.

Ecclesiastes 12:1-5 Remember thy Creator in the days of thy youth, before the time of affliction come, and the years draw nigh of which thou shalt say: They please me not: . . .

Deuteronomy 32:29 O that they would be wise and would understand, and would provide for their last end.

Job 10:22 A land of misery and darkness, where the shadow of death, and no order, but everlasting horror dwelleth.

Job 14:10 But man when he shall be dead, and stripped and consumed, I pray you where is he?

Job 15:23 When he moveth himself to seek bread, he knoweth that the day of darkness is ready at his hand.

Job 18:18 He shall drive him out of light into darkness, and shall remove him out of the world.

Jeremiah 13:16 Give ye glory to the Lord your God, before it be dark, and before your feet stumble upon the dark mountains: you shall look for light, and he will turn it into the shadow of death, and into darkness.

Joel 2:2 A day of darkness, and of gloominess, a day of clouds and whirlwinds: a numerous and strong people as the morning spread upon the mountains: the like to it hath not been from the beginning, nor shall be after it, even to the years of generation and generation.

Matthew 22:13 Then the king said to the waiters: Bind his hands and feet, and cast him into the exterior darkness. There shall be weeping and gnashing of teeth.

John 12:35 Jesus therefore said to them: Yet a little while, the light is among you. Walk whilst you have the light, and the darkness overtake you not. And he that walketh in darkness knoweth not whither be goeth.

Jude 1:18 Who told you that in the last time there should come mockers, walking according to their own desires in ungodlinesses.

all that

Ecclesiastes 2:1-11,15,17,19,21-23,26 I said in my heart: I will go, and abound with delights, and enjoy good things. And I saw that this also was vanity. . . .

Ecclesiastes 4:8,16 There is but one, and he hath not a second, no child, no brother, and yet he ceaseth not to labour, neither are his eyes satisfied with riches, neither doth he reflect, saying: For whom do I labour, and defraud my soul of good things? in this also is vanity, and a grievous vexation. . . .

Ecclesiastes 5:15,16 As he came forth naked from his mother's womb, so shall he return, and shall take nothing away with him of his labour. . . .

Ecclesiastes 6:11 There are many words that have much vanity in disputing.