John 1:8

He was not the light, but that he might witness concerning the light.

John 1:20

And he acknowledged and denied not, and acknowledged, I am not the Christ.

John 3:28

Ye yourselves bear me witness that I said, I am not the Christ, but, that I am sent before him.

Acts 19:4

And Paul said, John indeed baptised with the baptism of repentance, saying to the people that they should believe on him that was coming after him, that is, on 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
And he acknowledged and denied not, and acknowledged, I am not the Christ.
John 3:28
Ye yourselves bear me witness that I said, I am not the Christ, but, that I am sent before him.
Acts 19:4
And Paul said, John indeed baptised with the baptism of repentance, saying to the people that they should believe on him that was coming after him, that is, on Jesus.

General references

Mark 11:30
The baptism of John, was it of heaven, or of men? answer me.
Acts 13:24
John having proclaimed before the face of his entry among the people the baptism of repentance to all the people of Israel.