John 1:8

He was not the light, but was sent that he might testify about the light.

John 1:20

He declared, and didn't deny, but he declared, "I am not the Christ."

John 3:28

You yourselves testify that I said, 'I am not the Christ,' but, 'I have been sent before him.'

Acts 19:4

Paul said, "John indeed baptized with the baptism of repentance, saying to 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 declared, and didn't deny, but he declared, "I am not the Christ."
John 3:28
You yourselves testify that I said, 'I am not the Christ,' but, 'I have been sent before him.'
Acts 19:4
Paul said, "John indeed baptized with the baptism of repentance, saying to the people that they should believe in the one who would come after him, that is, in Jesus."

General references

Mark 11:30
The baptism of John -- was it from heaven, or from men? Answer me."
Acts 13:24
before his coming, when John had first preached the baptism of repentance to Israel.