{When they heard} (akouontes). Present active participle
of akou(935c), while hearing. {They were cut to the heart}
(dieprionto tais kardiais). See  5:33  where the same word and
form (imperfect passive of diapri(935c)) is used of the effect of
Peter's speech on the Sadducees. Here Stephen had sent a saw
through the hearts of the Pharisees that rasped them to the bone.
{They gnashed on him with their teeth} (ebruchon tous odontas
ep' auton). Imperfect (inchoative) active of ruch(935c) (Attic
ruk(935c)), to bite with loud noise, to grind or gnash the teeth.
Literally, They began to gnash their teeth at (ep') him (just
like a pack of hungry, snarling wolves). Stephen knew that it
meant death for him.