John 1:23

23 He said, "I am the voice of one crying out in the wilderness, "Make straight the way of the Lord,' " as the prophet Isaiah said.

John 1:23 In-Context

21 And they asked him, "What then? Are you Elijah?" He said, "I am not." "Are you the prophet?" He answered, "No."
22 Then they said to him, "Who are you? Let us have an answer for those who sent us. What do you say about yourself?"
23 He said, "I am the voice of one crying out in the wilderness, "Make straight the way of the Lord,' " as the prophet Isaiah said.
24 Now they had been sent from the Pharisees.
25 They asked him, "Why then are you baptizing if you are neither the Messiah, nor Elijah, nor the prophet?"
New Revised Standard Version Bible, copyright 1989, Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved.