Which knew me from the beginning, if they would testify, that after the most straitest sect of our religion I lived a Pharisee. After the most straitest sect - That is, the Pharisees; who were reputed the strictest in their doctrines, and in their moral practices, of all the sects then among the Jews. The sects were the Pharisees, Sadducees, and Essenes.
Related Commentaries of Acts 26:5
Acts 26:5
5 Which knew me from the beginning, if they would testify, that after the most straitest sect of our religion I lived a Pharisee.