1 Corinthians 5:9 - Ellicott's Commentary On The Whole Bible

I wrote unto you in an epistle. — These words have given rise to some controversy as to whether the Apostle here refers to some former Epistle addressed to the Corinthian Church, and which has not been preserved, or whether the reference is not to this Epistle itself. It has been suggested by some who adopt the latter view that these words may have been added as an interpolation after the completion of the Epistle, and be intended to intensify the remarks made by the Apostle on this subject in 1 Corinthians 5:6-8; 1 Corinthians 6:9-20. Such an interpretation, however, seems rather strained. It is more natural to suppose that the reference is to an Epistle written to the Corinthians, probably from Ephesus, after a visit paid to Corinth of which we have no record, for in 2 Corinthians 12:14; 2 Corinthians 13:1, we read of a third visit being contemplated, whereas only one previous one is recorded. (See also Introduction.) The condition of the Church which caused the Apostle that “heaviness,” which he connects with this visit in 2 Corinthians 2:1, would naturally have given rise to an Epistle containing the kind of direction here referred to.