Acts 21:21-24
They have been informed that you teach all the Jews who live among the Gentiles to reject Moses, telling them not to circumcise their children nor to live according to our customs.
What about this? Without a doubt, they will hear that you have arrived.
You must therefore do what we tell you. Four men among us have made a solemn promise.
Take them with you, go through the purification ritual with them, and pay the cost of having their heads shaved.