“You shall love your neighbor as yourself: I am the Lord,” says the book of Leviticus. Those last four words are not unrelated, as we will shortly see.
In Leviticus, the neighbor in question is
indisputably a fellow Israelite, a blood relative: “You shall not take
vengeance or bear a grudge against the sons of your own people, but you shall love your neighbor as yourself.” With the parable of the Good Samaritan, the definition of “neighbor” would shortly extend itself to moral geography a Jewish
legalist might not strictly consider his own stomping grounds, but that’s
another story. It isn’t part of the Sermon on the Mount.
We could import it, of course, but Jesus
didn’t.
The Good Samaritan is Luke’s tale to tell. Matthew,
who is all about the Lord’s Jewish audience, doesn’t touch it.