Matthew 18:16

But if he will not listen, take one or two others along with you, so that 'every matter may be established by the word of two or three witnesses.'

John 8:17

In your own law it is written that the testimony of two men is true.

2 Corinthians 13:1

This is the third time I am coming to you. Every charge must be established by the evidence of two or three witnesses.

1 Timothy 5:19

Do not receive an accusation against an elder except on the basis of two or three witnesses.

Hebrews 10:28

Anyone who has rejected the law of Moses dies without mercy on the testimony of two or three witnesses.

1 John 5:7-8

And it is the Spirit who bears witness, because the Spirit is the truth.

Revelation 11:3

And I will grant power to my two witnesses, and they will prophesy for twelve hundred and sixty days, clothed in sackcloth."

Treasury of Scripture Knowledge

Summary

But if he will not hear thee, then take with thee one or two more, that in the mouth of two or three witnesses every word may be established.

Bible References

That in

John 8:17
In your own law it is written that the testimony of two men is true.
2 Corinthians 13:1
This is the third time I am coming to you. Every charge must be established by the evidence of two or three witnesses.
1 Timothy 5:19
Do not receive an accusation against an elder except on the basis of two or three witnesses.
Hebrews 10:28
Anyone who has rejected the law of Moses dies without mercy on the testimony of two or three witnesses.
1 John 5:7
And it is the Spirit who bears witness, because the Spirit is the truth.
Revelation 11:3
And I will grant power to my two witnesses, and they will prophesy for twelve hundred and sixty days, clothed in sackcloth."