Isaiah 33:19
"Thou shalt not see a fierce people, a people of a deeper speech than thou canst perceive; of a stammering tongue, that thou canst not understand."
Cross References (ranked by relevance)
For with stammering lips and another tongue will he speak to this people.
Lo, I will bring a nation upon you from far, O house of Israel, saith the LORD: it is a mighty nation, it is an ancient nation, a nation whose language thou knowest not, neither understandest what they say.
And Moses said unto the people, Fear ye not, stand still, and see the salvation of the LORD, which he will shew to you to day: for the Egyptians whom ye have seen to day, ye shall see them again no more for ever.
Therefore thus saith the LORD concerning the king of Assyria, He shall not come into this city, nor shoot an arrow there, nor come before it with shield, nor cast a bank against it.
In the law it is written, With men of other tongues and other lips will I speak unto this people; and yet for all that will they not hear me, saith the LORD.