Acts 21:26
Then Paul took those men and the next day purified himself with them. Then he went into the Temple to announce the time when their days of purification would end and when the sacrifice would be offered for each of them.
Acts 24:18
They found me in the Temple doing these things just as I had completed the purification ceremony. No crowd or noisy mob was present.
Numbers 6:13-20
"This is the law of the Nazirite: When the days of his consecration are completed, he is to come to the entrance at the Tent of Meeting.
Acts 21:24
Take these men, go through the purification ceremony with them, and pay their expenses to shave their heads. Then everyone will know that there is nothing in what they have been told about you, but that you are carefully observing and keeping the Law.
1 Corinthians 9:20
To the Jews I became like a Jew in order to win Jews. To those under the Law I became like a man under the Law, in order to win those under the Law (although I myself am not under the Law).