Romans 4:4

Now to the one who works, wages are not credited as a gift but as an obligation.

(v4, NIV)

Now Paul embarks to explain the nature of works. What does it mean to work for something? So for the example of someone who works a job, how does he or she earn their pay? When a person works, they work to earn their wages. What they earn is what their employer owes them. Their wages are what they deserve. The nature of work is described as opposite to a gift.