When they had tied him up (o proeteinan auton). First aorist active indicative of proteinw, old verb to stretch forward, only here in the N.T. Literally, "When they stretched him forward." With the thongs (toi imasin). If the instrumental case of ima, old word for strap or thong (for sandals as Mark 1:7 , or for binding criminals as here), then Paul was bent forward and tied by the thongs to a post in front to expose his back the better to the scourges. But toi imasin may be dative case and then it would mean "for the lashes." In either case it is a dreadful scene of terrorizing by the chiliarch. Unto the centurion that stood by (pro ton estwta ekatontarcon). He was simply carrying out the orders of the chiliarch (cf. Matthew 27:54 ). Why had not Paul made protest before this? Is it lawful? (ei exestin?). This use of ei in indirect questions we have had before ( Matthew 1:6 ). A Roman and uncondemned (Romaion kai akatakriton). Just as in Matthew 16:37 which see. Blass says of Paul's question: Interrogatio subironica est confidentiae plena.