“Be ye therefore perfect, even as your Father which is in heaven is perfect.”
Matthew 5:48 — Greek Interlinear
Church Fathers on Matthew 5:48
The Lord has taught above that we must not resist one who offers any injury, but must be ready even to suffer more; He now further requires us to shew to them that do us wrong both love and its effects. And as the things that have gone before pertain to the completion of the righteousness of the Law, in like manner this last precept is to be referred to the completion of the law of love, which, according to the Apostle, is the fulfilling of the Law.
That by the command, 'Thou shalt love thy neighbour,' all mankind were intended, the Lord shewed in the parable of the man who was left half dead, which teaches us that our neighbour is every one who may happen at any time to stand in need of our offices of mercy; and this who does not see must be denied to none, when the Lord says, 'Do good to them that hate you.'
As that, Thou shalt not lust, was not spoken to the flesh, but to the spirit, so in this the flesh indeed is not able to love its enemy, but the spirit is able; for the love and hate of the flesh is in the sense, but of the spirit is in the understanding. If then we feel hate to one who has wronged us, and yet will not to act upon that feeling, know that our flesh hates our enemy, but our soul loves him.