fierce, &c. Reference to Pentateuch (Deuteronomy 28:49; Deuteronomy 28:50).
stammering. jabbering.
tongue. Put by Figure of speech Metonymy (of Cause), for the language spoken by it.
Related Commentaries of Isaiah 33:19
Isaiah 33:19
19 Thou shalt not see a fierce people, a people of a deeper speech than thou canst perceive; of a stammeringd tongue, that thou canst not understand.