Parallel
1 Corinthians 14:11
Nestle 1904 Greek New Testament · Berean Standard Bible
ἐὰν οὖν μὴ εἰδῶ τὴν δύναμιν τῆς φωνῆς ἔσομαι τῷ λαλοῦντι βάρβαρος καὶ ὁ λαλῶν ἐν ἐμοὶ βάρβαρος
If, then, I do not know the meaning of someone’s language, I am a foreigner (note: Literally a barbarian; twice in this verse) to the speaker, and he is a foreigner to me.