“I wrote unto you in an epistle not to company with fornicators:”
King James Version (KJV)
5:9 I wrote to you in a former epistle - And, doubtless, both St. Paul and the other apostles wrote many things which are not extant now. Not to converse - Familiarly; not to contract any intimacy or acquaintance with them, more than is absolutely necessary.
1Co 5:9 I wrote unto you in an epistle. He had written an earlier letter which has not been preserved, probably a short one, to which reference is made. So most commentators understand.