Acts 21:26
The next day Paul took the men and purified himself along with them. Then he went to the temple to give notice of the date when the days of purification would end and the offering would be made for each one of them.
Acts 24:18
As I was doing this, they found me purified in the temple, without any crowd or uproar. But there were some Jews from Asia
Acts 21:24
take these men and purify yourself along with them and pay their expenses, so that they may shave their heads. Thus all will know that there is nothing in what they have been told about you, but that you yourself live in observance of the law.
1 Corinthians 9:20
To the Jews I became as a Jew, in order to win Jews; to those under the law I became as one under the lawthough not being myself under the lawso that I might win those under the law.