John 1:8

He was not the light,
but he came to testify about the light.

John 1:20

He did not refuse to answer, but he declared: “I am not the Messiah.”

John 3:28

You yourselves can testify that I said, ‘I am not the Messiah, but I’ve been sent ahead of Him.’

Acts 19:4

Paul said, “John baptized with a baptism of repentance, telling the people that they should believe in the One who would come after him, that is, in Jesus.”

Treasury of Scripture Knowledge

Summary

He was not that Light, but was sent to bear witness of that Light.

General references

Bible References

That light

John 1:20
He did not refuse to answer, but he declared: “I am not the Messiah.”
John 3:28
You yourselves can testify that I said, ‘I am not the Messiah, but I’ve been sent ahead of Him.’
Acts 19:4
Paul said, “John baptized with a baptism of repentance, telling the people that they should believe in the One who would come after him, that is, in Jesus.”

General references

Mark 11:30
Was John’s baptism from heaven or from men? Answer Me.”
Acts 13:24
Before He came to public attention, John had previously proclaimed a baptism of repentance to all the people of Israel.

Holman Christian Standard Bible®, Copyright © 1999, 2000, 2002, 2003, 2009 by Holman Bible Publishers.