Heb harak, meaning "to grate the teeth", (Job 16:9; Ps 112:10; La 2:16), denotes rage or sorrow. (See also Ac 7:54; Mr 9:18.)
His anger tears [at me], and He harasses me. He gnashes His teeth at me. My enemy pierces me with His eyes.
The wicked man will see [it] and be angry; he will gnash his teeth in despair. The desire of the wicked will come to nothing.
All your enemies open their mouths against you. They hiss and gnash [their] teeth, saying, "We have swallowed [her] up. This is the day we have waited for! We have lived to see [it]."
Wherever it seizes him, it throws him down, and he foams at the mouth, grinds his teeth, and becomes rigid. So I asked Your disciples to drive it out, but they couldn't."
When they heard these things, they were enraged in their hearts and gnashed their teeth at him.
Holman Christian Standard Bible®, Copyright © 1999, 2000, 2002, 2003, 2009 by Holman Bible Publishers.