Was consenting (ēn suneudokōn). Periphrastic imperfect of suneudokeō, a late double compound (sun, eu, dokeō) that well describes Saul’s pleasure in the death (anairesis, taking off, only here in the N.T., though old word) of Stephen. For the verb, see note on Luk 23:32. Paul himself will later confess that he felt so (Act 22:20), coolly applauding the murder of Stephen, a heinous sin (Rom 1:32). It is a gruesome picture. Chapter 7 should have ended here.
On that day (en ekeinēi tēi hēmerāi). On that definite day, that same day as in Act 2:41.
A great persecution (diōgmos megas). It was at first persecution from the Sadducees, but this attack on Stephen was from the Pharisees so that both parties are now united in a general persecution that deserves the adjective “great.” See Mat 13:21 for the old word diōgmos from diōkō, to chase, hunt, pursue, persecute.
Were all scattered abroad (pantes diesparēsan). Second aorist passive indicative of diaspeirō, to scatter like grain, to disperse, old word, in the N.T. only in Act 8:1, Act 8:4; Act 11:19.
Except the apostles (plēn tōn apostolōn). Preposition plēn (adverb from pleon, more) with the ablative often in Luke. It remains a bit of a puzzle why the Pharisees spared the apostles. Was it due to the advice of Gamaliel in Act 5:34-40? Or was it the courage of the apostles? Or was it a combination of both with the popularity of the apostles in addition?