Matt 18:15-22
[size=+2]A[/size]t that time, Jesus saith to his disciples: But if thy brother shall offend against thee, go, and rebuke him between thee and him alone. And so on.

Homily by St. Augustine, Bishop of Hippo.
16th Sermon on the Words of the Lord, vol. x
[size=+2]W[/size]hy tell him his fault? Because he hath made thee smart by trespassing against thee? God forbid. If thou tell him his fault because thou lovest thyself, thou dost nothing. But if thou tell it him because thou lovest him, then dost thou do exceeding well. Hear now, in the words of the Gospel itself, for love of whom, thou oughtest to do it, of thyself, or of him. The Lord saith: If he shall hear thee, thou hast gained thy brother. Therefore it behoveth thee to do it for his sake, that thou mayest gain him; since, if thou so do, haply thou mayest gain him; whereas, if thou do it not, he may haply perish. Why then are there so many who reckon lightly of a trespass against their brother, and say I have done no great offence, for I have trespassed only against my fellow man? Deem it not light; thou hast trespassed, though it be against thy fellow man.

[size=+2]W[/size]ouldest thou know that thy trespass against thy brother hath destroyed thee? If he against whom thou hast trespassed tell thee thy fault between himself and thee alone, and thou hear him, he hath gained thee. Gained thee! And what signify those words, if it be not that thou, if thou be not gained, shalt perish? For if thou shouldest not otherwise perish, in what sense can he be said to gain thee? Therefore let no man deem it a light thing when he trespasseth against his brother. For the Apostle Paul saith in a certain place: When ye sin so against the brethren, and wound their weak conscience, ye sin against Christ. 1 Cor. viii. 12. We are all members of Christ. How dost thou not trespass against Christ, which trespassest against one of His members?

[size=+2]L[/size]et no man therefore say I have not trespassed against God, but only against my brother; that is, I have trespassed against my fellowman; and so the sin is light, if any at all. And perchance thou wilt argue that it is light, because it is quickly mended; thou hast trespassed against thy brother, but thou canst make satisfaction, and be right again; thou hast done the deadly thing quickly, and quickly canst thou find a remedy. O my brethren, which of us can hope for the kingdom of heaven, when we remember that the Gospel saith: “Whosoever shall say to his brother: Thou fool, shall be in danger of hell fire?” Matth. v. 22. It is a thought full of dread; but, lo! the remedy: If thou bring thy gift to the altar, and there rememberest that thy brother hath aught against thee, leave there thy gift before the altar, and go thy way; first be reconciled to thy brother, and then come and offer thy gift. God is not wroth that thou tarry or ever thou offer thy gift; for God seeketh thyself more than thy gift.