“Now to him that worketh is the reward not reckoned of grace, but of debt.”
King James Version (KJV)
4:4 Now to him that worketh - All that the law requires, the reward is no favour, but an absolute debt. These two examples are selected and applied with the utmost judgment and propriety. Abraham was the most illustrious pattern of piety among the Jewish patriarchs. David was the most eminent of their kings. If then neither of these was justified by his own obedience, if they both obtained acceptance with God, not as upright beings who might claim it, but as sinful creatures who must implore it, the consequence is glaring It is such as must strike every attentive understanding, and must affect every individual person.
Ro 4:4 To him that worketh. Who earns wages as a servant. To that one a reward is not reckoned of grace, a free gift, but "a debt". If one has rendered himself righteous by his works, this is true of him.