Romans 15:21 KJV

But as it is written, To whom he was not spoken of, they shall see: and they that have not heard shall understand.

The writing and preaching of the apostleThe apostle was persuaded that the Roman Christians were filled with a kind and affectionate spirit, as well as with knowledge. He had written to remind them...

Isaiah 52:15 So shall he sprinkle many nations; the kings shall shut their mouths at him: for that which had not been told them shall they see; and that which they had not heard shall they consider.
Isaiah 65:1 I am sought of them that asked not for me; I am found of them that sought me not: I said, Behold me, behold me, unto a nation that was not called by my name.

From OpenBible.info, most relevant first.

But Ἀλλὰ Alla ἀλλά Conjunction
as καθὼς kathōs καθώς Conjunction
it is written γέγραπται gegraptai γράφω Verb · perfect passive indicative, third person singular
To whom Οἷς Hois ὅς Pronoun · dative masculine plural
he αὐτοῦ autou αὐτός Pronoun · third person, genitive masculine singular
was ἀναγγέλλω anangéllō
not οὐκ ouk οὐ Adverb
spoken ἀνηγγέλη anēngelē ἀναγγέλλω Verb · aorist passive indicative, third person singular
of περὶ peri περί Preposition
they shall see ὄψονται opsontai Verb · future middle indicative, third person plural ὀπτάνομαι optánomai
and καὶ kai καί Conjunction
they οἳ hoi ὅς Pronoun · nominative masculine plural
that have ἀκούω akoúō
not οὐκ ouk οὐ Adverb
heard ἀκηκόασιν akēkoasin ἀκούω Verb · perfect active indicative, third person plural
shall understand συνήσουσιν synēsousin συνίημι Verb · future active indicative, third person plural

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