John Lightfoot on Luke 10:33

[But a certain Samaritan.] The Jews have no dealings with the Samaritans: that is, so as to be obliged by them for any courtesy done to them. But would this Jew, half dead, reject the kindness of the Samaritan at this time? This person being of a nation than which the Jews hated nothing more, is brought in shewing this kindness to the Jew, on purpose to give the plainer instance, who is our neighbour. It might seem more proper to have said, that the Samaritan acknowledged the wounded man for his neighbour in being so kind to him: but our Saviour intimates that he was the wounded man's neighbour; thereby teaching us that even a stranger, yea, an enemy (against the doctrine of their own schools), is no other than our neighbour.