John Calvin on Romans 2:6

6. Who will render to every one, etc. As he had to do with blind saintlings, who thought that the wickedness of their hearts was well covered, provided it was spread over with some disguises, I know not what, of empty works, he pointed out the true character of the righteousness of works, even that which is of account before God; and he did this, lest they should feel confident that it was enough to pacify him, if they brought words and trifles, or leaves only. But there is not so much difficulty in this verse, as it is commonly thought. For the Lord, by visiting the wickedness of the reprobate with just vengeance, will recompense them with what they have deserved: and as he sanctifies those whom he has previously resolved to glorify, he will also crown their good works, but not on account of any merit: nor can this be proved from this verse; for though it declares what reward good works are to have, it does yet by no means show what they are worth, or what price is due to them. And it is an absurd inference, to deduce merit from reward.