Matthew 9:38

Figuratively; When salvation was given to the Gentiles, then all cities and towns were enlightened by the power and entrance of Christ, and escaped every former sickness and infirmity. The Lord pities the people troubled with the violence of the unclean Spirit, and sick under the burden of the Law, and having no shepherd at hand to bestow on them the guardianship of the Holy Spirit. But of that gift there was a most abundant fruit, whose plenty far exceeded the multitude of those that drank thereof; how many soever take of it, yet an inexhaustible supply remains; and because it is profitable that there should be many to minister it, He bids us ask the Lord of the harvest, that God would provide a supply of reapers for the ministration of that gift of the Holy Spirit which was made ready; for by prayer this gift is poured out upon us from God.

But when the Son of God looked down from heaven upon the earth, to hear the groans of the captives, straight a great harvest began to ripen; for the multitude of the human race would never have come near to the faith, had not the Author of human salvation looked down from heaven; and it follows, Then said he unto his disciples, The harvest truly is great, but the labourers are few. For the number of the Apostles was small in comparison of so great crops to be reaped. The Lord exhorts His preachers, that is, the Apostles and their followers, that they should daily desire an increase of their number; Pray ye therefore the Lord of the harvest, that he would send forth labourers into his harvest. Or, He then increased their number when He chose the seventy and two, and then when many preachers were made what time the Holy Spirit descended upon the believers.

(Verse 37, 38.) Indeed, the harvest is plentiful, but the laborers are few. Therefore, pray to the Lord of the harvest to send out laborers into his harvest. The abundant harvest signifies the multitude of people, while the few laborers represent a shortage of workers. And it is commanded to pray to the Lord of the harvest to send out laborers into his harvest. These are the laborers whom the Psalmist speaks of, saying: Those who sow in tears will reap with joy. Going forth, they went and wept, carrying their seeds. But when they come, they will come with joy, carrying their sheaves (Psalm 126:7-8). And to speak more plainly, the abundant harvest is the entire crowd of believers. However, the workers are few, like the apostles and those who imitate them and are sent to the harvest.

And not even at this doth He stop, but He exhibits also another instance of His forethought. That is, "When He saw," it is said, "the multitudes, He was moved with compassion on them, because they were troubled, and scattered abroad, as sheep having no shepherd. Then saith He unto His disciples, The harvest truly is plenteous, but the laborers are few, pray ye therefore the Lord of the harvest, that He will send forth laborers into His harvest." See again His freedom from vainglory. That He may not draw all men unto Himself, He sends out His disciples. And not with this view only, but that He might also teach them, after practising in Palestine, as in a sort of training-school, to strip themselves for their conflicts with the world. For this purpose then He makes the exercises even more serious than the actual conflicts, so far as pertained to their own virtue; that they might more easily engage in the struggles that were to ensue; as it were a sort of tender nestlings whom He was at length leading out to fly. And for the present He makes them physicians of bodies, dispensing to them afterwards the cure of the soul, which is the principal thing. And mark how He points out the facility and necessity of the thing. For what saith He? "The harvest truly is plenteous, but the laborers are few." That is, "not to the sowing," saith He, "but to the reaping do I send you." Which in John He expressed by, "Other men labored, and ye are entered into their labors." And these things he said, at once repressing their pride, and preparing them to be of good courage, and signifying that the greater part of the labor came first. But of what laborers doth He speak here? Of the twelve disciples. What then? whereas He had said, "But the laborers are few," did He add to their number? By no means, but He sent them out alone. […]

Then to signify how great the gift is, He saith, "Pray ye the Lord of the harvest;" and indirectly declares it to be His own prerogative. For after having said, "Pray ye the Lord of the harvest;" when they had not made any entreaty nor prayer, He Himself at once ordains them, reminding them also of the sayings of John, of the threshing floor, and of the Person winnowing, and of the chaff, and of the wheat. Whence it is evident that Himself is the husbandman, Himself the Lord of the harvest, Himself the master and owner of the prophets. For if He sent them to reap, clearly it was not to reap what belongs to another, but what Himself had sown by the prophets. But not in this way only was He indirectly encouraging them, in calling their ministry a harvest; but also by making them able for the ministry.