Acts 21:26
Then Paul took the men, and after purifying himself with them next day, went into the temple to declare the fulfilment of the days of purification, until the offering was offered for every one of them.
Acts 24:18
"While I was thus engaged, they found me in the temple, purified, with no crowd and no uproar. But there were certain Asiatic Jews
Acts 21:24
"We have four men here under a vow; associate yourself with them, purify yourself with them, and pay their expenses so that they may have their heads shaved; then every one will know that there is no truth in the rumors that they have heard about you; but that you yourself walk orderly obeying the law.
1 Corinthians 9:20
To the Jews I am become like a Jew, that I may win Jews; to those under the Law, like one under the Law, though I am not under the Law, myself;