Ecclesiastes 4:1 is another observation of futility under the sun, here oppression, while 4:7 turns to loneliness—both illustrate meaninglessness.

Ecclesiastes 1:3 asks what gain there is in all toil under the sun — the foundational question that underlies the vanity observed in 4:7.

Psalm 39:6 echoes the same futility: man heaps up wealth but does not know who will gather it — directly reinforcing the vanity of solitary labor.