Luke 17:3

After the parable of the rich man who is tormented in punishment, Christ added a commandment to give forgiveness to those who turn themselves from their trespasses, lest any one through despair should not be reclaimed from his fault; and hence it is said, Take heed to yourselves.

As if He says, Offenses must needs come; but it does not follow that you must perish, if only you be on your guard: as it need not that the sheep should perish when the wolf comes, if the shepherd is watching. And since there are great varieties of offenders, (for some are incurable, some are curable,) He therefore adds, If your brother trespass against you, rebuke him.

That there might neither be hard-wrung pardon, nor a too easy forgiveness, neither a harsh upbraiding, to dishearten, nor an overlooking of faults, to invite to sin; therefore it is said in another place, Tell him his fault between him and you alone. For better is a friendly correction, than a quarrelsome accusation. The one strikes shame into a man, the other moves his indignation. He who is admonished will more likely be saved, because he fears to he destroyed. For it is well that he who is corrected should believe you to be rather his friend than his enemy. For we have readily give ear to counsel than yield to injury. Fear us a weak preserver of consistency, but shame is an excellent master of duty. For he who fears is restrained, not amended. But He has well said, If he trespass against you. For it is not the same thing to shun against God and to sin against man.

But we must mark, that He does not bid us forgive every one who sins, but him only who repents of his sins. For by taking this course we may avoid offenses, hurting no one, correcting the sinner with a righteous zeal, extending the bowels of mercy to the penitent.

But some one may well ask, If when I have several times forgiven my brother he again trespass against me, what must I do with him? In answer therefore to this question He adds, And if he trespass against you seven times in a day, and seven times in a day turn again to you, saying, I repent; forgive him.

By using the number seven He assigns no bound to the giving of pardon, but commands us either to forgive all sins, or always to forgive the penitent. For by seven the whole of any thing or time is frequently represented.

Or this number is used because God rested on the seventh day from His works. After the seventh day of the world everlasting rest is promised us, that as the evil works of that world shall then cease, so also may the sharpness of punishment be abated.

Further, in respect to forbearance. “If thy brother,” it is said, “sin against thee, rebuke him; and if he repent, forgive him. If he sin against thee seven times in a day, and turn to thee the seventh time, and say, I repent, forgive him.” Also to the soldiers, by John, He commands, “to be content with their wages only;” and to the publicans, “to exact no more than is appointed.” To the judges He says, “Thou shalt not show partiality in judgment. For gifts blind the eyes of those who see, and corrupt just words. Rescue the wronged.”

Then, turning to His disciples, He says: “Woe unto him through whom offences come! It were better for him if he had not been born, or if a millstone were hanged about his neck and he were cast into the sea, than that he should offend one of these little ones,” that is, one of His disciples. Judge, then, what the sort of punishment is which He so severely threatens. For it is no stranger who is to avenge the offence done to His disciples. Recognise also in Him the Judge, and one too, who expresses Himself on the safety of His followers with the same tenderness as that which the Creator long ago exhibited: “He that toucheth you toucheth the apple of my eye.” Such identity of care proceeds from one and the same Being. A trespassing brother He will have rebuked. …

74. It is this difference in their sins which separates Judas the betrayer from Peter the denier: not that a penitent is not to be pardoned, for we must not come into collision with that declaration of our Lord, where He enjoins that a brother is to be pardoned, when he asks his brother to pardon him; but that the ruin connected with that sin is so great, that he cannot endure the humiliation of asking for it, even if he should be compelled by a bad conscience both to acknowledge and divulge his sin. For when Judas had said, “I have sinned, in that I have betrayed the innocent blood,” yet it was easier for him in despair to run and hang himself, than in humility to ask for pardon. And therefore it is of much consequence to know what sort of repentance God pardons. …

On the words of the Gospel, Luke xvii. 3 , “If thy brother sin, rebuke him,” etc., touching the remission of sins.

But what presses harder upon the present question [in the Lord’s command of praying for enemies and persecutors] is that saying of the apostle John, “If any man know that his brother sinneth a sin not unto death, he shall ask, and the Lord will give life to that man who sinneth not unto death: but there is a sin unto death: not for that do I say that he should ask.” For it manifestly shows that there are some “brethren” whom we are not commanded to pray for, whereas the Lord bids us pray even for our persecutors. Nor can this question be solved except we acknowledge, that there are some sins in brethren that are worse than the sin of enemies in persecuting. …