John 1:7

This man came for a testimony, to testify of the light, that all might believe through him.

John 1:19

AND this is the testimony of John, when the Jews from Jerusalem sent priests and Levites to ask him, Who are you?

Acts 19:4

Paul said, John indeed baptized [administered] the baptism of a change of mind, telling the people to believe on him that was to come after him, that is, on Jesus.

John 1:9

The light was the true [light] which lights every man that comes into the world.

John 1:12

But as many as received him, to them gave he power to become sons of God, to them that believe on his name,

John 1:15

John testified of him, and cried, saying, This is the one of whom I said, He that comes after me existed before me, for he was before me.

John 1:26-27

John answered them saying, I baptize with water; but among you stands one whom you know not.

John 1:32-34

And John testified saying, I saw the Spirit descend like a dove from heaven, and it remained on him.

John 1:36

and looking at Jesus as he walked, he said, Behold the Lamb of God.

John 3:26-36

And they came to John and said to him, Rabbi, he that was with you beyond the Jordan, to whom you testified, behold, this [man] baptizes and all men come to him.

John 5:33-35

You sent to John, and he testified to the truth;

Ephesians 3:9

and to enlighten all men as to the dispensation of the mystery concealed from eternity in God who created all things,

1 Timothy 2:4

who wishes all men to be saved and to come to a knowledge of truth.

Titus 2:11

For the grace of God that pertains to salvation appeared to all men,

2 Peter 3:9

The Lord is not slow in respect to his promise, as some men account slowness, but is long-suffering toward us, not willing that any should perish, but that all should come to a change of mind.

Treasury of Scripture Knowledge

Summary

The same came for a witness, to bear witness of the Light, that all men through him might believe.

General references

Bible References

A witness

John 1:19
AND this is the testimony of John, when the Jews from Jerusalem sent priests and Levites to ask him, Who are you?
John 3:26
And they came to John and said to him, Rabbi, he that was with you beyond the Jordan, to whom you testified, behold, this [man] baptizes and all men come to him.
John 5:33
You sent to John, and he testified to the truth;
Acts 19:4
Paul said, John indeed baptized [administered] the baptism of a change of mind, telling the people to believe on him that was to come after him, that is, on Jesus.

That

John 1:9
The light was the true [light] which lights every man that comes into the world.
John 3:26
And they came to John and said to him, Rabbi, he that was with you beyond the Jordan, to whom you testified, behold, this [man] baptizes and all men come to him.
Ephesians 3:9
and to enlighten all men as to the dispensation of the mystery concealed from eternity in God who created all things,
1 Timothy 2:4
who wishes all men to be saved and to come to a knowledge of truth.
Titus 2:11
For the grace of God that pertains to salvation appeared to all men,
2 Peter 3:9
The Lord is not slow in respect to his promise, as some men account slowness, but is long-suffering toward us, not willing that any should perish, but that all should come to a change of mind.

General references

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