1 John 5:9

If we accept [as we do] the testimony of men [that is, if we are willing to take the sworn statements of fallible humans as evidence], the testimony of God is greater [far more authoritative]; for this is the testimony of God, that He has testified regarding His Son.

Matthew 3:16-17

After Jesus was baptized, He came up immediately out of the water; and behold, the heavens were opened, and he (John) saw the Spirit of God descending as a dove and lighting on Him (Jesus),

John 10:38

But if I am doing them, even if you do not believe Me or have faith in Me, [at least] believe the works [that I do—admit that they are the works of God], so that you may know and keep on knowing [clearly—without any doubt] that the Father is in Me, and I am in the Father [that is, I am One with Him].”

Matthew 17:5

While he was still speaking, behold, a bright cloud overshadowed them, and a voice from the cloud said, “This is My beloved Son, with whom I am well-pleased and delighted! Listen to Him!”

John 3:32-33

What He has [actually] seen and heard, of that He testifies; and yet no one accepts His testimony [as true].

John 5:31-37

“If I alone testify about Myself, My testimony is not valid.

John 5:39

You search and keep on searching and examining the Scriptures because you think that in them you have eternal life; and yet it is those [very Scriptures] that testify about Me;

John 8:17-19

Even in your own law it is written that the testimony of two persons is true [valid and admissible].

Acts 5:32

And we are witnesses of these things; and so is the Holy Spirit, whom God has bestowed on those who obey Him.”

Acts 17:31

because He has set a day when He will judge the inhabited world in righteousness by a Man whom He has appointed and destined for that task, and He has provided credible proof to everyone by raising Him from the dead.”

Hebrews 2:4

[and besides this evidence] God also testifying with them [confirming the message of salvation], both by signs and wonders and by various miracles [carried out by Jesus and the apostles] and by [granting to believers the] gifts of the Holy Spirit according to His own will.

Hebrews 6:18

so that by two unchangeable things [His promise and His oath] in which it is impossible for God to lie, we who have fled [to Him] for refuge would have strong encouragement and indwelling strength to hold tightly to the hope set before us.

1 John 5:10

The one who believes in the Son of God [who adheres to, trusts in, and relies confidently on Him as Savior] has the testimony within himself [because he can speak authoritatively about Christ from his own personal experience]. The one who does not believe God [in this way] has made Him [out to be] a liar, because he has not believed in the evidence that God has given regarding His Son.

Treasury of Scripture Knowledge

Summary

If we receive the witness of men, the witness of God is greater: for this is the witness of God which he hath testified of his Son.

Bible References

We

1 John 5:10
The one who believes in the Son of God [who adheres to, trusts in, and relies confidently on Him as Savior] has the testimony within himself [because he can speak authoritatively about Christ from his own personal experience]. The one who does not believe God [in this way] has made Him [out to be] a liar, because he has not believed in the evidence that God has given regarding His Son.
John 3:32
What He has [actually] seen and heard, of that He testifies; and yet no one accepts His testimony [as true].
John 5:31
“If I alone testify about Myself, My testimony is not valid.
John 8:17
Even in your own law it is written that the testimony of two persons is true [valid and admissible].
John 10:38
But if I am doing them, even if you do not believe Me or have faith in Me, [at least] believe the works [that I do—admit that they are the works of God], so that you may know and keep on knowing [clearly—without any doubt] that the Father is in Me, and I am in the Father [that is, I am One with Him].”
Acts 5:32
And we are witnesses of these things; and so is the Holy Spirit, whom God has bestowed on those who obey Him.”
Acts 17:31
because He has set a day when He will judge the inhabited world in righteousness by a Man whom He has appointed and destined for that task, and He has provided credible proof to everyone by raising Him from the dead.”
Hebrews 2:4
[and besides this evidence] God also testifying with them [confirming the message of salvation], both by signs and wonders and by various miracles [carried out by Jesus and the apostles] and by [granting to believers the] gifts of the Holy Spirit according to His own will.
Hebrews 6:18
so that by two unchangeable things [His promise and His oath] in which it is impossible for God to lie, we who have fled [to Him] for refuge would have strong encouragement and indwelling strength to hold tightly to the hope set before us.

For

Matthew 3:16
After Jesus was baptized, He came up immediately out of the water; and behold, the heavens were opened, and he (John) saw the Spirit of God descending as a dove and lighting on Him (Jesus),
Matthew 17:5
While he was still speaking, behold, a bright cloud overshadowed them, and a voice from the cloud said, “This is My beloved Son, with whom I am well-pleased and delighted! Listen to Him!”