It is essential to observe that this parable relates to service, for the laborers are sent into the vineyard. There is also no doubt that it sprang out of Peter's question: "Behold, we have forsaken all, and followed Thee; what shall we have therefore?" In reply the Lord graciously told His disciples that they should have a special place in the kingdom -should sit on twelve thrones, judging the twelve tribes of Israel—and, moreover, that everyone who had forsaken anything for His name's sake should be abundantly recompensed. He then added the significant warning, that many who were first should be last, and the last first. And this He proceeded to explain in the parable: "For," He says, "the kingdom of heaven is like unto a man that is a householder, which went out early in the morning, to hire laborers into his vineyard."
We have, in the next place, a description of the several laborers, with the different hours at which they were hired. But, in fact, there are but two classes—those who agreed upon the amount they were to receive, and those who left themselves in the hands of the master to give what he deemed right. The former, we apprehend, being the "first," and the latter the "last" of chapter 19:30. The former too represent, we doubt not, the spirit of Peter, as expressed in his question, "What shall we have therefore?" The Lord thus brings before us the right and wrong spirit of service—the latter finding its motive in expected reward, whereas the former draws the spring of its activity from the will of the master, and is content to leave every other question to the grace which has called. The one thinks of the value of the labor rendered, the other of the master for whom the service is done. Those who agreed for their penny were, in a word, legal servants, whereas those who left themselves to the one who had called them were under the power of grace. To the first, the labor was a means of recompense; to the last, it was a privilege, and hence they prize it in and for itself, knowing something of the grace that has bestowed it. All this is brought out when the steward settles with the laborers. In obedience to his lord he begins with the last, and everyone received a penny. This excited the anger of the first; for if the last had a penny, surely they were entitled to more. The answer was that they had received what they bargained for, that the master had a right to do what he would with his own, and that their eye was not to be evil because he was good.
The exhibition of grace, with all its sovereign rights, only excited the envy of the natural heart. Hence the enmity of the Jew when the gospel was proclaimed to the Gentile; and thus, though the "first," he also became the "last." So with these laborers. Those who went to labor last in the vineyard left the master's presence satisfied with his goodness, and so became "first"; while those who were first in their labors left his presence with murmurs in their hearts and on their lips, strangers still to grace. Hence the conclusion: So the last shall be first (referring to chapter 19:30), and the first last; for many be called (as all these laborers had been), but few chosen.