Matthew 20:8

8.And when the evening was come. It would be improper to look for a mystery in the injunction of the householder to begin with the last, as if God crowned those first who were last in the order of time; for such a notion would not at all agree with the doctrine of Paul. They that are alive, he says, at the coming of Christ will not come before those who previously fell asleep in Christ, but will follow, (1 Thessalonians 4:15.) But Christ observes a different order in this passage, because he could not otherwise have expressed — what he afterwards adds — that the first murmured, because they did not receive more (646)

Besides, he did not intend to say that this murmuring will take place at the last day, but merely to affirm that there will be no occasion for murmuring The personification ( προσωποποΐα) which he employs throws no small light on this doctrine, that men have no right to complain of the bounty of God, when he honors unworthy persons by large rewards beyond what they deserve. There is no foundation, therefore, for what some have imagined, that these words are directed against the Jews, who were full of malice and envy towards the Gentiles; for it would be absurd to say that such persons receive an equal hire with the children of God, and this malignity, which leads men to exclaim against God, does not apply to believers. But the plain meaning is, that, since God defrauds no man of a just hire, He is at liberty to bestow on those whom He has lately called an undeserved reward.