ISB ~ Matthew 5 v43

love your neighbor:A reference to Lev 19:18. Jesus considers it one of the two great commandments of the Mosaic Law (22:39). Unlike Jesus, however, some Jews held a narrow interpretation of neighbor, restricting it only to one’s fellow Israelite (cf. Lk 10:29-37) (CCC 1933).

hate your enemy:Probably a reference to Israel’s warfare laws in Deut 20. Because Gentiles in Canaan worshiped false gods, they were enemies of God. Moses thus called Israel to exterminate them under Joshua and the Judges, lest Israel imitate their idolatry (cf. Ex 23:32-33; Ps 139:19-22). Against this background, Jesus counters Jewish disdain for Gentiles who continue to live in Palestine. He broadens the meaning of neighbor to include Gentiles, even their Roman persecutors. The Father’s impartial treatment of all people is a model for Christian mercy (5:45).