Deuteronomy 19:15

"A single witness shall not suffice against a person for any crime or for any wrong in connection with any offense that he has committed. Only on the evidence of two witnesses or of three witnesses shall a charge be established.

Numbers 35:30

"If anyone kills a person, the murderer shall be put to death on the evidence of witnesses. But no person shall be put to death on the testimony of one witness.

Matthew 18:16

But if he does not listen, take one or two others along with you, that every charge may be established by the evidence of two or three witnesses.

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.

Deuteronomy 17:6

On the evidence of two witnesses or of three witnesses the one who is to die shall be put to death; a person shall not be put to death on the evidence of one witness.

John 8:17

In your Law it is written that the testimony of two people is true.

1 Timothy 5:19

Do not admit a charge against an elder except on the evidence of two or three witnesses.

Hebrews 10:28

Anyone who has set aside the law of Moses dies without mercy on the evidence of two or three witnesses.

1 Kings 21:10

And set two worthless men opposite him, and let them bring a charge against him, saying, 'You have cursed God and the king.' Then take him out and stone him to death."

1 Kings 21:13

And the two worthless men came in and sat opposite him. And the worthless men brought a charge against Naboth in the presence of the people, saying, "Naboth cursed God and the king." So they took him outside the city and stoned him to death with stones.

Matthew 26:60-61

but they found none, though many false witnesses came forward. At last two came forward

Revelation 11:3-7

And I will grant authority to my two witnesses, and they will prophesy for 1,260 days, clothed in sackcloth."

Treasury of Scripture Knowledge

Summary

One witness shall not rise up against a man for any iniquity, or for any sin, in any sin that he sinneth: at the mouth of two witnesses, or at the mouth of three witnesses, shall the matter be established.

Bible References

At the mouth

Deuteronomy 17:6
On the evidence of two witnesses or of three witnesses the one who is to die shall be put to death; a person shall not be put to death on the evidence of one witness.
Numbers 35:30
"If anyone kills a person, the murderer shall be put to death on the evidence of witnesses. But no person shall be put to death on the testimony of one witness.
1 Kings 21:10
And set two worthless men opposite him, and let them bring a charge against him, saying, 'You have cursed God and the king.' Then take him out and stone him to death."
Matthew 18:16
But if he does not listen, take one or two others along with you, that every charge may be established by the evidence of two or three witnesses.
Matthew 26:60
but they found none, though many false witnesses came forward. At last two came forward
John 8:17
In your Law it is written that the testimony of two people 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 admit a charge against an elder except on the evidence of two or three witnesses.
Hebrews 10:28
Anyone who has set aside the law of Moses dies without mercy on the evidence of two or three witnesses.
Revelation 11:3
And I will grant authority to my two witnesses, and they will prophesy for 1,260 days, clothed in sackcloth."

General references

Numbers 35:30
"If anyone kills a person, the murderer shall be put to death on the evidence of witnesses. But no person shall be put to death on the testimony of one witness.
Deuteronomy 17:6
On the evidence of two witnesses or of three witnesses the one who is to die shall be put to death; a person shall not be put to death on the evidence of one witness.
John 7:51
"Does our law judge a man without first giving him a hearing and learning what he does?"

The Holy Bible, English Standard Version® copyright © 2001 by Crossway Bibles, a publishing ministry of Good News Publishers.