From: Luke 9:51-62
Some Samaritans Refuse to Receive Jesus
When the days drew near for Him (Jesus) to be received up, He set His face to go to Jerusalem. And He sent messengers ahead of Him, who went and entered a village of the Samaritans, to make ready for Him; but the people would not receive Him, because His face was set toward Jerusalem. And when His disciples James and John saw it, they said, "Lord, do You want us to bid fire come down from Heaven and consume them?" But He turned and rebuked them. And they went on to another village.
The Calling of Three Disciples
As they were going along the road, a man said to Him, "I will follow you wherever You go." And Jesus said to him, "Foxes have holes, and birds of the air have nests; but the Son of Man has nowhere to lay His head." To another He said, "Follow Me." But he said, "Lord, let me first go and bury my father."  But He said to him, "Leave the dead to bury their own dead; but as for you, go and proclaim the Kingdom of God." Another said, "I will follow You, Lord; but let me first say farewell to those at my home." Jesus said to him, "No one who puts his hand to the plough and looks back is fit for the Kingdom of God."
51. "When the days drew near for Him to be received up": these words refer to the moment when Jesus will leave this world and ascend into Heaven. Our Lord will say this more explicitly during the Last Supper: "I come from the Father and have come into the world; again, I am leaving the world and going to the Father" (John 16:28). By making His way resolutely to Jerusalem, towards His Cross, Jesus freely complies with His Father's plan for His passion and death to be the route to His resurrection and ascension.
52-53. The Samaritans were hostile towards the Jews. This enmity derived from the fact that the Samaritans were descendants of marriages of Jews with Gentiles who repopulated the region of Samaria at the time of the Assyrian captivity (in the eight century before Christ). There were also religious differences: the Samaritans had mixed the religion of Moses with various superstitious practices, and did not accept the temple of Jerusalem as the only place where sacrifices could properly be offered. They built their own temple on Mount Gerizim, in opposition to Jerusalem (cf. John 4:20); this was why, when they realized Jesus was headed for the Holy City, they refused Him hospitality.
54-56. Jesus corrects His disciples' desire for revenge, because it is out of keeping with the mission of the Messiah, who has come to save men, not destroy them (cf. Luke 19:10; John 12:47). The Apostles are gradually learning that zeal for the things of God should not be bitter or violent.
"The Lord does everything in an admirable way [...]. He acts in this way to teach us that perfect virtue retains no desire for vengeance, and that where there is true charity there is no room for anger--in other words, that weakness should not be treated with harshness but should be helped. Indignation should be very far from holy souls, and desire for vengeance very far from great souls" (St. Ambrose, "Expositio Evangelii Sec. Lucam, in loc.").
An RSV footnote after the word "rebuked" in verse 55 points out that other ancient authorities add "and He said `You do not know what manner of Spirit you are of; for the Son of Man came not to destroy men's lives but to save them'". These words appear in a considerable number of early Greek MSS and other versions and were included in the Clementine Vulgate; but they do not appear in the best and oldest Greek codexes and have not been included in the New Vulgate.
57-62. Our Lord spells out very clearly what is involved in following Him. Being a Christian is not an easy or comfortable affair: it calls for self-denial and for putting God before everything else. See the notes on Matthew 8:18-22 and Matthew 8:22.
We see here the case of the man who wanted to follow Christ, but on one condition--that he be allowed to say goodbye to his family. Our Lord, seeing that he is rather undecided, gives him an answer which applies to all of us, for we have all received a calling to follow Him and we have to try not to receive this grace in vain. "We receive the grace of God in vain, when we receive it at the gate of our heart, and do not let it enter our heart. We receive it without receiving it, that is, we receive it without fruit, since there is no advantage in feeling the inspiration if we do not accept it [...]. It sometimes happens that being inspired to do much we consent not to the whole inspiration but only to some part of it, as did those good people in the Gospel, who upon the inspiration which our Lord gave them to follow Him wished to make reservations, the one to go first and bury his father, the other to go to take leave of his people" (St. Francis de Sales, "Treatise on the Love of God", Book 2, Chapter 11).
Our loyalty and fidelity to the mission God has given us should equip us to deal with every obstacle we meet: "There is never reason to look back (cf. Luke 9:62). The Lord is at our side. We have to be faithful and loyal; we have to face up to our obligations and we will find in Jesus the love and the stimulus we need to understand other people's faults and overcome our own" ([Saint] J. Escriva, "Christ Is Passing By", 160).
Source: "The Navarre Bible: Text and Commentaries". Biblical text taken from the Revised Standard Version and New Vulgate. Commentaries made by members of the Faculty of Theology of the University of Navarre, Spain. Published by Four Courts Press, Kill Lane, Blackrock, Co. Dublin, Ireland. Reprinted with permission from Four Courts Press and Scepter Publishers, the U.S. publisher.