en_tn/php/03/05.md

I was circumcised

This can be stated in active form. Alternate translation: "A priest circumcised me" (See: rc://en/ta/man/translate/figs-activepassive)

on the eighth day

"seven days after I was born"

a Hebrew of Hebrews

Possible meanings are 1) "a Hebrew son with Hebrew parents" or 2) "the purest Hebrew."

with regard to the law, a Pharisee

The Pharisees were committed to obeying all of the law. Being a Pharisee showed that Paul was committed to obeying all of the law. Alternate translation: "as a Pharisee, I was committed to obeying all of the law"