Isaiah 33:19

You will no longer see the insolent, a people whose speech is unintelligible, who stammer in a language you cannot understand.
BSB · Berean Standard Bible
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.

Note stammering: or, ridiculous

KJV · King James Version
You will no longer see the fierce people, a people of a deep speech that you can’t comprehend, with a strange language that you can’t understand.
WEB · World English Bible
Thou shalt not see the fierce people, a people of a deep speech that thou canst not comprehend, of a strange tongue that thou canst not understand.
ASV · American Standard Version

Related passages

From the Treasury of Scripture Knowledge, grouped by the word they explain.

shall not
Exodus 14:13; Deuteronomy 28:49, 50; 2 Kings 19:32
deeper
Isaiah 28:11; Jeremiah 5:15; Ezekiel 3:5, 6; 1 Corinthians 14:21