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.)
Wherever it seizes him, it throws him down and he foams at the mouth, grinds his teeth and stiffens out. I spoke to your disciples, asking them to drive it out, but they were not able to."
Now when the Council members heard these things they were enraged and ground their teeth at him.