G4258–προαμαρτάνω–proamartanō

that again when I come my God would humble me before you, and I would mourn for many of those who have sinned before now, and not repented of the uncleanness and sexual immorality and lustfulness which they committed.

προημαρτηκότων proēmartēkotōn “having sinned before”

I have said beforehand, and I do say beforehand, as when I was present the second time, so now, being absent, I write to those who have sinned before now, and to all the rest, that, if I come again, I will not spare;

προημαρτηκόσιν proēmartēkosin “having sinned before”