'Unintelligible' in the Bible

You will no longer see a fierce people,A people of unintelligible speech which no one comprehends,Of a stammering tongue which no one understands.

For you are not being sent to a people of unintelligible speech or difficult language, but to the house of Israel,

nor to many peoples of unintelligible speech or difficult language, whose words you cannot understand. But I have sent you to them who should listen to you;