Albert Barnes on Acts 22:29

Then straightway. Immediately. They saw that by scourging him they would have violated the Roman law, and exposed themselves to its penalty.

Which should have examined him. Who were about to torture him by scourging him, Acts 22:24.

Because he had bound him. Preparatory to scourging him. The act of binding a Roman citizen, with such an intent, untried and uncondemned, was unlawful. Prisoners who were to be scourged were usually bound by the Romans to a pillar or post; and a similar custom prevailed among the Jews. That it was unlawful to bind a man, with this intent, who was uncondemned, appears from an express declaration in Cicero, (against Vetres.) "It is a heinous sin to bind a Roman citizen; it is wickedness to beat him; it is next to parricide to kill him; and what shall I say to crucify him?"

(+) "straightway" "immediately" (1) "examined"