Ecclesiastes 3:10

I have seen the travail, which God hath given to the sons of men to be exercised in it.

Cross-reference

Ecclesiastes 1:13 uses the same phrase 'burden God has laid' to introduce the Preacher's search for wisdom under heaven.

Ecclesiastes 2:26 specifies that God gives the burden of gathering to sinners, while giving wisdom to the righteous.

Ecclesiastes 1:14 concludes that the burden leads to meaninglessness, a chasing after wind.

Ecclesiastes 8:9 observes the burden of human oppression under the sun, continuing the theme of life's difficulties.

Genesis 3:19 describes the curse of painful labor and death — the original burden God laid on fallen humanity.