Acts 16:1-3

And he came also to Derbe and to Lystra: and behold, a certain disciple was there, named Timothy, the son of a Jewess that believed; but his father was a Greek. The same was well reported of by the brethren that were at Lystra and Iconium. Him would Paul have to go forth with him; and he took and circumcised him because of the Jews that were in those parts: for they all knew that his father was a Greek.