Albert Barnes Commentary Acts 22:25

"And when they had tied him up with the thongs, Paul said unto the centurion that stood by, Is it lawful for you to scourge a man that is a Roman, and uncondemned?" — Acts 22:25 (ASV)

Bound him with thongs. With cords, preparatory to scourging.

Is it lawful, etc. It was directly contrary to the Roman law, to bind and scourge a Roman citizen. See Barnes on Acts 16:36.