Acts 23:17

Then Paul called one of the centurions, &c. The Apostle was under the charge of a military guard, and so would have no difficulty in getting his message conveyed. And the knowledge that he was a Roman citizen, and that by birth, would have spread among the soldiery and would not be without its influence.

for he hath a certain thing[Rev. Ver. something] to tell him We have nothing to guide us to a knowledge of how Paul's nephew became acquainted with the plot to murder his uncle. As we know nothing of any kinsmen of St Paul being Christians we may perhaps be right in supposing that the young man was a Jew, present in Jerusalem on account of the feast, and that he had heard among the Jewish population about the uproar, and the undertaking of the would-be assassins. In his interview with the chief captain it is clear that he was prepared with evidence which was convincing to that officer.