Ecclesiastes 1:3 asks the same question — 'what gain from toil?' — reinforcing the theme of futility.

Ecclesiastes 2:11 concludes all toil is vanity — answering the 'what gain' question with 'nothing'.

Ecclesiastes 2:22 repeats the same question about gain from toil — echoing the refrain of futility.

Ecclesiastes 2:23 describes toil as sorrow and vexation — directly answering that there is no gain, only pain.

Ecclesiastes 5:16 asks 'what gain?' for toiling for wind — reinforcing the emptiness of labor.

Proverbs 14:23 asserts there is profit in toil — directly opposing Ecclesiastes' skeptical question about gain.

In Matthew 16:26, Jesus asks what profit there is in gaining the world but losing one's soul — extending the question of gain to eternal stakes.