John Chrysostom — as excerpted in the Catena Aurea on Matthew 18:18-20

“And be it noted, that He said not to the Primate1 of the Church, Bind such a man; but, If ye shall bind him, the bonds shall be indissoluble; leaving the other to his discretion. And see how He has set the incorrigible person under the yoke of a twofold necessity; to wit, the punishment that is here, namely, the casting forth out of the Church, when He said, Let him be to thee as a heathen; and the future punishment, saying, that he shall be bound in heaven; thus by the weight of his penalties lessening his brother’s wrath against him.”