John 1:8

He was not the Light, but sent that he should bear testimony concerning the Light.

John 1:20

And he confessed, and denied it not; but acknowledged, I am not the Messiah.

John 3:28

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

Acts 19:4

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

General references

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