Who were the saints Paul shut up in prison?
The saints Paul shut up in prison were Jewish saints, Jewish believers. He received authority not from Caesar or Rome but from the chief priests, and he imprisoned many of them in Jerusalem. These were fellow Jews who had believed, and Paul acted under the religious authority of the chief priests.
Les explains that when Paul says, "and many of the saints did I shut up in prison," those saints were Jewish saints, Jewish believers. Paul was reflecting back in the first person as the apostle, and he had received authority not from Caesar or Rome but from the chief priests. Les notes that Rome allowed the Jewish people to carry out capital punishment in the name of their religion, and there was no opposition to that. So Paul's imprisonment of these believers was done under the authority of the chief priests, not the Roman government.