Matthew 5:43

We have here, lastly, an exposition of that great fundamental law of the second table, Thou shalt love thy neighbour, which was the fulfilling of the law. I. See here how this law was corrupted by the comments of the Jewish teachers, Mat 5:43. God said, Thou shalt love thy neighbour; and by neighbour they understood those only of their own country, nation, and religion; and those only that they were pleased to look upon as their friends: yet this was not the worst; from this command, Thou shalt love thy neighbour, they were willing to infer what God never designed; Thou shalt hate thine enemy; and they looked upon whom they pleased as their enemies, thus making void the great command of God by their traditions, though there were express laws to the contrary, Exo 23:4, Exo 23:5; Deu 23:7. Thou shalt not abhor an Edomite, nor an Egyptian, though these nations had been as much enemies to Israel as any whatsoever. It was true, God appointed them to destroy the seven devoted nations of Canaan, and not to make leagues with them; but there was a particular reason for it - to make room for Israel, and that they might not be snares to them; but it was very ill-natured from hence to infer, that they must hate all their enemies; yet the moral philosophy of the heathen then allowed this.

— Matthew Henry's Concise Commentary (public domain)

Ye have heard that it hath been said-- (Lev 19:18). Thou shalt love thy neighbour--To this the corrupt teachers added, and hate thine enemy--as if the one were a legitimate inference from the other, instead of being a detestable gloss, as BENGEL indignantly calls it. LIGHTFOOT quotes some of the cursed maxims inculcated by those traditionists regarding the proper treatment of all Gentiles. No wonder that the Romans charged the Jews with hatred of the human race.

— Jamieson-Fausset-Brown Commentary (public domain)