A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
mat 20:1PARABLE OF THE LABORERS IN THE VINEYARD. (Mat. 20:1-16)
For the kingdom of heaven is like unto a man that is an householder, &c.--The figure of a vineyard, to represent the rearing of souls for heaven, the culture required and provided for that purpose, and the care and pains which God takes in that whole matter, is familiar to every reader of the Bible. (Psa 80:8-16; Isa 5:1-7; Jer 2:21; Luk 20:9-16; Joh 15:1-8). At vintage time, as WEBSTER and WILKINSON remark, labor was scarce, and masters were obliged to be early in the market to secure it. Perhaps the pressing nature of the work of the Gospel, and the comparative paucity of laborers, may be incidentally suggested, Mat 9:37-38. The "laborers," as in Mat 9:38, are first, the official servants of the Church, but after them and along with them all the servants of Christ, whom He has laid under the weightiest obligation to work in His service.
mat 20:2And when he had agreed with the labourers for a penny--a usual day's hire.
he sent them into his vineyard.
mat 20:3And he went out about the third hour--about nine o'clock, or after a fourth of the working day had expired: the day of twelve hours was reckoned from six to six.
and saw others standing idle in the market place--unemployed.
mat 20:4And said unto them, Go ye also into the vineyard; and whatsoever is right--just, equitable, in proportion to their time.
I will give you. And they went their way.
mat 20:5Again he went out about the sixth and ninth hour--about noon, and about three o'clock in the afternoon.
and did likewise--hiring and sending into his vineyard fresh laborers each time.
mat 20:6And about the eleventh hour--but one hour before the close of the working day; a most unusual hour both for offering and engaging
and found others standing idle, and saith, Why stand ye here all the day idle?--Of course they had not been there, or not been disposed to offer themselves at the proper time; but as they were now willing, and the day was not over, and "yet there was room," they also are engaged, and on similar terms with all the rest.
mat 20:8So when even was come--that is, the reckoning time between masters and laborers (see Deu 24:15); pointing to the day of final account.
the lord of the vineyard saith unto his steward--answering to Christ Himself, represented "as a Son over His own house" (Heb 3:6; see Mat 11:27; Joh 3:35; Joh 5:27).
Call the labourers and give them their hire, beginning from the last unto the first--Remarkable direction this--last hired, first paid.
mat 20:9And when they came that were hired about the eleventh hour, they received every man a penny--a full day's wages.
mat 20:10But when the first came, they supposed that they should have received more--This is that calculating, mercenary spirit which had peeped out--though perhaps very slightly--in Peter's question (Mat 19:27), and which this parable was designed once for all to put down among the servants of Christ.
mat 20:11And when they had received it, they murmured against the goodman of the house--rather, "the householder," the word being the same as in Mat 20:1.
mat 20:12Saying, These last have wrought but one hour, and thou hast made them equal unto us, which have borne the burden and heat--the burning heat.
of the day--who have wrought not only longer but during a more trying period of the day.
mat 20:13But he answered one of them--doubtless the spokesman of the complaining party.
and said, Friend, I do thee no wrong: didst not thou agree with me for a penny? &c.
mat 20:15Is it not lawful for me to do what I will with mine own? Is thine eye evil, because I am good?--that is, "You appeal to justice, and by that your mouth is shut; for the sum you agreed for is paid you. Your case being disposed of, with the terms I make with other laborers you have nothing to do; and to grudge the benevolence shown to others, when by your own admission you have been honorably dealt with, is both unworthy envy of your neighbor, and discontent with the goodness that engaged and rewarded you in his service at all."
mat 20:16So the last shall be first, and the first last--that is, "Take heed lest by indulging the spirit of these murmurers at the penny given to the last hired, ye miss your own penny, though first in the vineyard; while the consciousness of having come in so late may inspire these last with such a humble frame, and such admiration of the grace that has hired and rewarded them at all, as will put them into the foremost place in the end."
for many be called, but few chosen--This is another of our Lord's terse and pregnant sayings, more than once uttered in different connections. (See Mat 19:30; Mat 22:14). The "calling" of which the New Testament almost invariably speaks is what divines call effectual calling, carrying with it a supernatural operation on the will to secure its consent. But that cannot be the meaning of it here; the "called" being emphatically distinguished from the "chosen." It can only mean here the "invited." And so the sense is, Many receive the invitations of the Gospel whom God has never "chosen to salvation through sanctification of the Spirit and belief of the truth" (Th2 2:13). But what, it may be asked, has this to do with the subject of our parable? Probably this--to teach us that men who have wrought in Christ's service all their days may, by the spirit which they manifest at the last, make it too evident that, as between God and their own souls, they never were chosen workmen at all.