Matthew 18:16

But if he will not listen, take one or two others with you, so that everything may be supported by the testimony of two or three witnesses.

John 8:17

Why, in your own Law it is stated that the testimony of two persons is valid.

2 Corinthians 13:1

This will be my third visit to you. Any charge must be sustained by the evidence of two or three witnesses.

1 Timothy 5:19

Do not listen to an accusation made against an elder, unless it is supported by two or three witnesses.

Hebrews 10:28

Anyone who breaks the Law of Moses is put to death without any show of pity, on the evidence of only two or three witnesses.

1 John 5:7-8

For there are three that testify to it,

Revelation 11:3

And I will permit my two witnesses, clothed in sackcloth, to prophesy for 1,260 days."

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
Why, in your own Law it is stated that the testimony of two persons is valid.
2 Corinthians 13:1
This will be my third visit to you. Any charge must be sustained by the evidence of two or three witnesses.
1 Timothy 5:19
Do not listen to an accusation made against an elder, unless it is supported by two or three witnesses.
Hebrews 10:28
Anyone who breaks the Law of Moses is put to death without any show of pity, on the evidence of only two or three witnesses.
1 John 5:7
For there are three that testify to it,
Revelation 11:3
And I will permit my two witnesses, clothed in sackcloth, to prophesy for 1,260 days."