12 Lo! I forewarn, and testify, and proclaim this with a voice that all may hear! “Let no one who has an enemy draw near the sacred Table, or receive the Lord's Body! Let no one who draws near have an enemy! Have you an enemy? Draw not near! Will you draw near? Be reconciled, and then draw near, and touch the Holy Thing!” Nor, indeed, is this my declaration. Rather it is that of the Lord Himself, Who was crucified for us. That He might reconcile you to the Father, He refused not to be sacrificed, and to shed His blood!
And are you unwilling to utter a word, or to make the first advance, that you may be reconciled to your fellow-servant? Hear what the Lord says, concerning those who are in this disposition; “If you bring your gift to the altar, and there rememberest that your brother has anything against you”— He does not say, “wait for him to come to you,” nor “speak with another as mediator,” nor “entreat some other,” but “do you yourself make the advance towards him.” For the exhortation is, “Go your way, first be reconciled to your brother.” O transcendent wonder!
Does He Himself account it no dishonour, that the gift should be left unoffered, and do you think it a mark of disgrace to go first and be reconciled? And how can such a case, I ask, be deemed worthy of pardon? Were you to see a member of yours cut off, would you not use every exertion so that it might be reunited to the body? This do with regard to your brethren; when you see them cut off from your friendship, make all haste to recover them! Do not wait for them to make the first advance, but press onward, that you may be foremost to receive the prize.
Source: Homilies on the Statues (New Advent)