Luke 9:51-56

"As the time approached for him to be taken up to heaven, Jesus resolutely set out for Jerusalem. And he sent messengers on ahead, who went into a Samaritan village to get things ready for him; but the people there did not welcome him, because he was heading for Jerusalem. When the disciples James and John saw this, they asked, 'Lord do you want us to call fire down from heaven to destroy them?' But Jesus turned and rebuked them. Then he and his disciples went to another village." Luke 9:51-56

Matthew Henry's Concise Commentary
The disciples did not consider that the conduct of the Samaritans was rather the effect of national prejudices and bigotry, than of enmity to the word and worship of God; and through they refused to receive Christ and his disciples, they did not ill use or injure them, so that the case was widely different from that of Ahaziah and Elijah. Nor were they aware that the gospel dispensation was to be marked by miracles of mercy. But above all, they were ignorant of the prevailing motives of their own hearts, which were pride and carnal ambition. Of this our Lord warned them. It is easy for us to say, Come, see our zeal for the Lord! and to think we are very faithful in his cause, when we are seeking our own objects, and even doing harm instead of good to others.

IVP New Testament Commentary
Jesus sends messengers ahead to prepare the people for his arrival. Much like an advance public relations team, they were to help plan what would occur when he arrived. But the Samaritans did not welcome him. The explanation is that Jesus' face is set toward Jerusalem. In other words, rejection is his fate. Even though that rejection will occur in the capital of Israel, the Samaritan reaction mirrors that coming reality. The world is not responsive to Jesus; rejection is widespread.

The disciples react with the wish to use their connections and power to launch a retributive strike. James and John ask for the ancient equivalent of nuking the enemy: "Lord, do you want us to call fire down from heaven to destroy them?"The disciples understand the great power they have access to, but the question is whether vindictive use of this power is proper. Is their hostile reaction justified? The request for "fire from above" recalls the ministry of Elijah (2 Kings 1). In their view, surely rejection means instant judgment.

Jesus corrects them. The text does not tell us what he said. In a story that is a little unusual in form, it simply notes that Jesus rebukes them and they move on to the next village. Many Gospel accounts end with a climactic saying of Jesus, a pronouncement that is key to the event in question. Here Jesus' action speaks for itself. There is no saying; rather, the disciples' saying becomes a view to be rejected emphatically. The disciples are not to wield their power as a club of judgment. Vindication from God will come later, as he deals with those who reject him. Warnings can be issued, as in 9:5, 10:13-16 or 17:20-36, but God is giving people time to decide to come to him. So the disciples are to preach the opportunity for salvation. If they are not well received, they are to move on. So having left this Samaritan city, Jesus and the disciples continue their mission in another village.