Charles Ellicott Commentary Matthew 5:43

"Ye have heard that it was said, Thou shalt love thy neighbor, and hate thine enemy:" — Matthew 5:43 (ASV)

You shall love your neighbor and hate your enemy. In its form, the latter clause was a Rabbinic addition to the former. This is important, as it shows that our Lord deals throughout not with the Law as such, but with the scribes’ exposition of it. However, it can hardly be said that these words, as far as national enemies were concerned, were foreign to the spirit of the Law. The Israelites were practically commanded to hate the Canaanites and Amalekites, whom they were commissioned to destroy. The fault of the scribes was that they treated the Law—which was temporary in its nature—as rigid and permanent, extending it in the wrong direction by making it a justification for indulging in private hatreds.

Our Lord cancels this Rabbinic gloss regarding national and, à fortiori, private hatreds. He teaches us to strive for the ideal excellence that He Himself realized: to love—that is, to seek the good of—those who have shown us the most bitter hostility. Thus, He taught people to find a neighbor even in a Samaritan, and so He prayed, Father, forgive them, for they do not know what they do.