Adam Clarke's Commentary on the Bible

Verse 18 (Matthew 18:18)

Whatsoever ye shall bind, etc. - Whatever determinations ye make, in conformity to these directions for your conduct to an offending brother, will be accounted just, and ratified by the Lord. See on Matthew 16:19 ; (note); and, to what is there said, the following observations may be profitably added.

Οσα εαν δησητε - και οσα εαν λυσητε . Binding and loosing, in this place, and in Matthew 16:19 , is generally restrained, by Christian interpreters, to matters of discipline and authority. But it is as plain as the sun, by what occurs in numberless places dispersed throughout the Mishna, and from thence commonly used by the later rabbins when they treat of ritual subjects, that binding signified, and was commonly understood by the Jews at that time to be, a declaration that any thing was unlawful to be done; and loosing signified, on the contrary, a declaration that any thing may be lawfully done. Our Savior spoke to his disciples in a language which they understood, so that they were not in the least at a loss to comprehend his meaning; and its being obsolete to us is no manner of reason why we should conclude that it was obscure to them. The words, bind and loose, are used in both places in a declaratory sense, of things, not of persons. It is ὁ and ὃσα , in the neuter gender, both in chap. 16, and here in this: i.e. Whatsoever thing or things ye shall bind or loose. Consequently, the same commission which was given at first to St. Peter alone, ( Matthew 16:19 ;), was afterwards enlarged to all the apostles. St. Peter had made a confession that Jesus was the Christ, the Son of God. His confession of the Divinity of our Lord was the first that ever was made by man; to him, therefore, were given the keys of the kingdom of heaven: i.e. God made choice of him among all the apostles, that the Gentiles should first, by his mouth, hear the word of the Gospel, and believe. He first opened the kingdom of heaven to the Gentiles, when he preached to Cornelius. It was open to the Jews all along before; but if we should suppose that it was not, yet to them also did St. Peter open the kingdom of heaven, in his sermon at the great pentecost. Thus, then, St. Peter exercised his two keys: that for the Jews at the great pentecost; and that for the Gentiles, when he admitted Cornelius into the Church. And this was the reward of his first confession, in which he owned Jesus to be the promised Messiah. And what St. Peter loosed, i.e. declared as necessary to be believed and practised by the disciples here, was ratified above. And what he declared unlawful to be believed and practised, (i.e. what he bound), was actually forbidden by God himself.

I own myself obliged to Dr. Lightfoot for this interpretation of the true notion of binding and loosing. It is a noble one, and perfectly agrees with the ways of speaking then in use among the Jews. It is observable that these phrases, of binding and loosing, occur no where in the New Testament but in St. Matthew, who is supposed to have written his Gospel first in Hebrew, from whence it was translated into Greek, and then the force and use of the expression will better appear. Dr. Wotton's Miscell. Discourses, vol. i. p. 309, etc., etc.

"The phrases to bind and to loose were Jewish, and most frequent in their writers. It belonged only to the teachers among the Jews to bind and to loose. When the Jews set any apart to be a preacher, they used these words, 'Take thou liberty to teach what is Bound and what is Loose.'" Strype's preface to the Posthumous Remains of Dr. Lightfoot, p. 38.

- Adam Clarke's Commentary on the Bible