'Purification' in the Bible

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.

Then Paul took the men, and the next day purifying himself with them entered into the temple, to signify the accomplishment of the days of purification, until that an offering should be offered for every one of them.

They found me in the Temple doing these things just as I had completed the purification ceremony. No crowd or noisy mob was present.