Matthew 9:36 – 10:8
9:36 But when he saw the multitudes, he was moved with compassion on them, because they fainted, and were scattered abroad, as sheep having no shepherd.37 Then saith he unto his disciples, The harvest truly is plenteous, but the labourers are few; 38 Pray ye therefore the Lord of the harvest, that he will send forth labourers into his harvest.10:1 And when he had called unto him his twelve disciples, he gave them power against unclean spirits, to cast them out, and to heal all manner of sickness and all manner of disease. 2 Now the names of the twelve apostles are these; The first, Simon, who is called Peter, and Andrew his brother; James the son of Zebedee, and John his brother;3 Philip, and Bartholomew; Thomas, and Matthew the publican; James the son of Alphaeus, and Lebbaeus, whose surname was Thaddaeus; 4 Simon the Canaanite, and Judas Iscariot, who also betrayed him.5 These twelve Jesus sent forth, and commanded them, saying, Go not into the way of the Gentiles, and into any city of the Samaritans enter ye not:6 But go rather to the lost sheep of the house of Israel. 7 And as ye go, preach, saying, The kingdom of heaven is at hand.8 Heal the sick, cleanse the lepers, raise the dead, cast out devils: freely ye have received, freely give.
"No instigator had stirred up the crowds. They were not harassed and helpless because of some mishap or disturbance. So why is Jesus so moved with compassion for these people? Clearly the Lord has pity on these people held in the sway of an unclean spirit and burdened by the law, because no shepherd was about to restore to them the guardianship of the Holy Spirit. The fruit of this gift was indeed potentially abundant but not yet harvested by anyone. The bounty of the Spirit overwhelms the multitude of those who take hold of it. For no matter how much it is gathered by everyone, it abounds in fruitfulness. And because it is good to have many people through whom he is served, he orders his disciples to pray to the Lord of the harvest to send forth as many laborers as possible into the harvest. He prays that God may bestow an abundance of reapers to take hold of what the gift of the Holy Spirit was preparing. Through prayer and exhortation, God pours out this gift upon us." (On Matthew 10:2)
St. John Chrysostom said regarding those Jesus and the disciples went to (in Homilies According to St. Matthew 9 and 10):
"And so far from punishing them for their insensibility, He did not even simply rebuke them; at once both evincing His meekness, and so refuting the calumny; and at the same time minded also by the signs which followed to exhibit His proof more completely; and then to adduce also the refutation by words. He went about therefore both in cities, and in countries, and in their synagogues; instructing us to requite our calumniators, not with fresh calumnies, but with greater benefits. Since, if not for man's sake, but God's, thou doest good to thy fellow-servants; whatsoever they may do, leave not thou off doing them good, that thy reward may be greater; since he surely, who upon their calumny leaves off his doing good, signifies that for their praise sake, not for God's sake, he applies himself to that kind of virtue.
"For this cause Christ, to teach us that of mere goodness He had entered on this, so far from waiting for the sick to come to Him, of Himself hastened unto them, bearing them two of the greatest blessings; one, the gospel of the kingdom; another, the perfect cure of all their diseases. And not a city did He overlook, not a village did He hasten by, but visited every place."
The Path's Thomas Soroko refers to the command to not preach to the Gentiles and quotes the same St. Hilary of Poitier I included above:
"It is because they did not have the law…they are warned to avoid the ways of the Gentiles, not because they were never going to be sent for the salvation of the Gentiles, but because they were to avoid the works and the lifestyle of the unenlightened Gentiles. They were forbidden to enter the towns of the Samaritans, yet did he not cure the Samaritan woman? They were warned, moreover, not to go into the assemblies of heretics. For heterodoxy does not differ at all from unenlightenment. Therefore, they were being sent to the lost sheep of Israel who raged against him with the tongues and jaws of wolves and vipers. At any rate, the law was due to receive the special benefit of the gospel. The less excuse Israel had for its good behavior, the more zeal it might have in heeding the warning."