“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:”
These twelve Jesus sent out, instructing them, Go nowhere among the Gentiles and enter no town of the Samaritans. The mission's first limitation surprises readers who know the great commission of Matthew 28:19 — go to all nations. The restriction to Israel in this initial mission is not the final word but the first chapter: Israel must be offered the kingdom first (Romans 1:16 — to the Jew first and also to the Greek). The limited mission to Israel during Jesus' earthly ministry will give way to the unlimited mission after the resurrection. The Samaritan restriction reflects the historical Jewish-Samaritan tension; Jesus will himself engage Samaritans in John 4, and the disciples will be sent to Samaria in Acts 1:8.
Church Fathers on Matthew 10:5
Because the manifestation of the Spirit, as the Apostle speaks, is given for the profit of the Church, after bestowing His power on the Apostles, He sends them that they may exercise this power for the good of others; 'These twelve Jesus sent forth.'
Observe the propriety of the time in which they are sent. After they had seen the dead raised, the sea rebuked, and other like wonders, and had both in word and deed sufficient proof of His excellent power, then He sends them.
This passage does not contradict the command which He gave afterwards, 'Go and teach all nations;' for this was before His resurrection, that was after. And it behoved the coming of Christ to be preached to the Jews first, that they might not have any just plea, or say that they were rejected of the Lord, who sent the Apostles to the Gentiles and Samaritans.