Parallel
Isaiah 33:19
King James Version (1769 Blayney revision, with Apocrypha) · Berean Standard Bible
Thou shalt not see a fierce people, a people of a deeper speech than thou canst perceive; of a stammering (note: Or, ridiculous) tongue, that thou canst not understand.
You will no longer see the insolent, a people whose speech is unintelligible, who stammer in a language you cannot understand.