ἀντιφωνεῖν

From LSJ

πάντες γὰρ οἱ λαβόντες μάχαιραν ἐν μαχαίρῃ ἀπολοῦνται → all they that take the sword shall perish with the sword

Source

Greek > English (Woodhouse Verbs Reversed)

(see also ἀντιφωνέω): contradict