1 Corinthians 14:11

ἐὰν οὖν μὴ εἰδῶ τὴν δύναμιν τῆς φωνῆς ἔσομαι τῷ λαλοῦντι βάρβαρος καὶ ὁ λαλῶν ἐν ἐμοὶ βάρβαρος