Acts 7:54

"Cut to the quick" is a figure of speech that describes being painfully wounded. Stephen’s charge of always resisting God’s Spirit convicted and offended the members of the Sanhedrin. They retaliated fiercely. Gnashing (grinding) the teeth pictures brutal antagonism.

"The possibilities are that what took place was a spontaneous act of mob violence or that Stephen was legally executed by the Sanhedrin, either because there was some kind of special permission from the Romans or because there was no Roman governor at the time and advantage was taken of the interregnum. The first of these possibilities is the more likely." [Note: Marshall, The Acts . . ., p. 148.]