For you will be His witness to all men of what you have seen and heard.
Acts 22:15
Surrounding context
22:14 Then he said, "The God of our fathers has chosen you that you should know His will, and see the Just One, and hear the voice of His mouth.
22:15 For you will be His witness to all men of what you have seen and heard.
22:16 And now why are you waiting? Arise and be baptized, and wash away your sins, calling on the name of the Lord.'