ἐν ἀπορρήτῳ λέγειν

From LSJ

ὦ πολλῶν ἤδη λοπάδων τοὺς ἄμβωνας περιλείξας → you who have licked the labia of many vaginas (Eupolis fr. 52)

Source

Greek > English (Woodhouse)

inform confidentially, inform in strict confidence