hagnizō

(Translation from NRSV with a few modifications for a more literal meaning)

John

11: 55

Now the Passover of the Jews was near, and many went up from the country to Jerusalem before the Passover to purify (hagnizō) themselves.

Acts

21: 24	Join these men, purify (hagnizō) yourself with them, and pay for the shaving of their heads. Thus all will know that there is nothing in what they have been told about you, but that you yourself observe and guard the law.
21: 26	Then Paul took the men, and the next day, having purified (hagnizō) himself, he entered the temple with them, making public the completion of the days of purification when the sacrifice would be made for each of them.
24: 18	While I was doing this, they found me in the temple being purified (hagnizō), without any crowd or disturbance.

1 John

3: 3	And all who have this hope in him purify (hagnizō) themselves, just as he is pure.