John 1:21-23

21They asked him, “Then who are you? Are you Elijah?” He said, “I am not.” “Are you the Prophet?” He answered, “No.”

22Finally they said, “Who are you? Give us an answer to take back to those who sent us. What do you say about yourself?”

23John replied in the words of Isaiah the prophet, “I am the voice of one calling in the wilderness, ‘Make straight the way for the Lord.’ ” Isaiah 40:3