'Purifying' in the Bible

Now there were six waterpots of stone set there after the Jews manner of purifying, containing two or three firkins apiece.

There arose therefore a questioning on the part of John's disciples with a Jew about purifying.

Then Paul took the men, and the next day purifying himself with them went into the temple, declaring the fulfilment of the days of purification, until the offering was offered for every one of them.