John 1:19-28 (ESV)
The Testimony of John the Baptist
19 And this is the testimony of John, when the Jews sent priests and Levites from Jerusalem to ask him, “Who are you?” 20 He confessed, and did not deny, but confessed, “I am not the Christ.” 21 And they asked him, “What then? Are you Elijah?” He said, “I am not.” “Are you the Prophet?” And he answered, “No.” 22 So they said to him, “Who are you? We need to give an answer to 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, “Then why are you baptizing, if you are neither the Christ, nor Elijah, nor the Prophet?” 26 John answered them, “I baptize with water, but among you stands one you do not know, 27 even he who comes after me, the strap of whose sandal I am not worthy to untie.” 28 These things took place in Bethany across the Jordan, where John was baptizing.