Deuteronomy 19:15

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

Numbers 35:30

"'Whoever kills any person, the murderer shall be slain at the mouth of witnesses: but one witness shall not testify against any person that he die.

Matthew 18:16

But if he does not listen, take one or two more with you, that at the mouth of two or three witnesses every word may be established.

2 Corinthians 13:1

This is the third time I am coming to you. "At the mouth of two or three witnesses shall every word be established."

Deuteronomy 17:6

At the mouth of two witnesses, or three witnesses, shall he who is to die be put to death; at the mouth of one witness he shall not be put to death.

John 8:17

It's also written in your Law that the testimony of two people is valid.

1 Timothy 5:19

Do not receive an accusation against an elder, except at the word of two or three witnesses.

Hebrews 10:28

A man who disregards the Law of Moses dies without compassion on the word of two or three witnesses.

1 Kings 21:10

Set two men, base fellows, before him, and let them testify against him, saying, 'You cursed God and the king.' Then carry him out, and stone him to death."

1 Kings 21:13

The two men, the base fellows, came in and sat before him. The base fellows testified against him, even against Naboth, in the presence of the people, saying, "Naboth cursed God and the king." Then they carried him out of the city, and stoned him to death with stones.

Matthew 26:60-61

and they found none. Even though many false witnesses came forward. But at last two false witnesses came forward,

Revelation 11:3-7

I will give power to my two witnesses, and they will prophesy one thousand two hundred sixty 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
At the mouth of two witnesses, or three witnesses, shall he who is to die be put to death; at the mouth of one witness he shall not be put to death.
Numbers 35:30
"'Whoever kills any person, the murderer shall be slain at the mouth of witnesses: but one witness shall not testify against any person that he die.
1 Kings 21:10
Set two men, base fellows, before him, and let them testify against him, saying, 'You cursed God and the king.' Then carry him out, and stone him to death."
Matthew 18:16
But if he does not listen, take one or two more with you, that at the mouth of two or three witnesses every word may be established.
Matthew 26:60
and they found none. Even though many false witnesses came forward. But at last two false witnesses came forward,
John 8:17
It's also written in your Law that the testimony of two people is valid.
2 Corinthians 13:1
This is the third time I am coming to you. "At the mouth of two or three witnesses shall every word be established."
1 Timothy 5:19
Do not receive an accusation against an elder, except at the word of two or three witnesses.
Hebrews 10:28
A man who disregards the Law of Moses dies without compassion on the word of two or three witnesses.
Revelation 11:3
I will give power to my two witnesses, and they will prophesy one thousand two hundred sixty days, clothed in sackcloth."

General references

Numbers 35:30
"'Whoever kills any person, the murderer shall be slain at the mouth of witnesses: but one witness shall not testify against any person that he die.
Deuteronomy 17:6
At the mouth of two witnesses, or three witnesses, shall he who is to die be put to death; at the mouth of one witness he shall not be put to death.
John 7:51
"Does our Law judge a man, unless it first hears from him personally and knows what he does?"