Leviticus explicitly defines the neighbor as one of "the children of thy people", thus excluding outsiders (who are enslaveable in perpetuity):
Thou shalt not avenge, nor bear any grudge against the children of thy people, but thou shalt love thy neighbour as thyself: I am the LORD. -- Leviticus 19:18
Jesus believed similarly, including about Samaritans (contra Luke 10:36):
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: But go rather to the lost sheep of the house of Israel. -- Matthew 10:5f.
This is in keeping also with the narrow scope of Jesus' conception of enemy love:
For I have come to set a man against his father, a daughter against her mother, and a daughter-in-law against her mother-in-law; And a man's enemies will be those of his own household. -- Matthew 10:35f.
For son dishonors father,
Daughter rises against her mother,
Daughter-in-law against her mother-in-law;
A man's enemies are the men of his own household. -- Micah 7:6
