A.T. Robertson Commentary Acts 22:20

"and when the blood of Stephen thy witness was shed, I also was standing by, and consenting, and keeping the garments of them that slew him." — Acts 22:20 (ASV)

Was shed (εξεχυννετο). Imperfect passive of εκχυννω , was being shed.

Witness (μαρτυρος). And "martyr" also as in Re 2:13; 17:6. Transition state for the word here.

I also was standing by (κα αυτος ημην εφεστως). Periphrastic second past perfect in form, but imperfect (linear) in sense since εστωσ=ισταμενος (intransitive).

Consenting (συνευδοκων). The very word used by Luke in Ac 8:1 about Paul. Koine word for being pleased at the same time with (cf. Luke 11:48). Paul adds here the item of "guarding the clothes of those who were slaying (αναιρουντων as in Lu 23:32; Acts 12:2) him" (Stephen). Paul recalls the very words of protest used by him to Jesus. He did not like the idea of running away to save his own life right where he had helped slay Stephen. He is getting on dangerous ground.