'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.

You are not being sent to many peoples of unintelligible speech or difficult language, whose words you cannot understand. No doubt, if I sent you to them, they would listen to you.