Church Fathers on Matthew 18:19

Because He had said, 'If he will not hear the Church, let him be to thee as a heathen, and a publican,' whereupon the brother so contemned might answer, or think within himself, If you despise me, I also will despise you; if you condemn me, you shall be condemned by my sentence. He therefore confers powers upon the Apostles, that they may be assured that when any are condemned after this manner, the sentence of man is ratified by the sentence of God. 'Verily I say unto you,…

He said not in the heavens (in caelis), as when He spoke to Peter, but in heaven (in coelo), for they are not yet attained to the like perfection with Peter.

To hold out a great and terrible fear, by which all men should be reached in this present life, He pronounces that the judgment of the Apostles should be ratified, so that whosoever they bound on earth, i.e. left entangled in the noose of sin, and whosoever they loosed, i.e. accorded the pardon of God’s mercy to their salvation, that these should be bound and loosed in heaven.'