John Calvin Commentary Matthew 20:16

"So the last shall be first, and the first last." — Matthew 20:16 (ASV)

So the first shall be last. He does not now compare the Jews to the Gentiles (as in another passage), nor the reprobate, who swerve from the faith, to the elect who persevere; and therefore the sentence introduced by some interpreters, many are called, but few are chosen, does not apply to that point. Christ only meant to say that everyone who has been called before others ought to run with so much the greater alacrity and, next, to exhort all people to be modest, not to give themselves preference over others, but willingly to share a common prize with them.

As the apostles were the first-fruits of the whole church, they appeared to possess some superiority; and Christ did not deny that they would sit as judges to govern the twelve tribes of Israel. But, so they would not be carried away by ambition or vain confidence in themselves, it was also necessary to remind them that others, who would be called long afterwards, would be partakers of the same glory. For God is not limited to any person, but freely calls whomever He pleases and bestows on those who are called whatever rewards He thinks fit.