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 the matter be established.

Numbers 35:30

Whoever kills any person, the murderer shall be put to death by the mouth of witnesses: but one witness shall not testify against any person to cause him to die.

Matthew 18:16

But if he will not hear you, then take with you one or two more, that in 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. In 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 that is worthy of death be put to death; but at the mouth of one witness he shall not be put to death.

John 8:17

It is also written in your law, that the testimony of two men is true.

1 Timothy 5:19

Against an elder receive not an accusation, unless before two or three witnesses.

Hebrews 10:28

He that despised Moses' law died without mercy under two or three witnesses:

1 Kings 21:10

And set two men, sons of Belial, before him, to bear witness against him, saying, You did blaspheme God and the king. And then carry him out, and stone him, that he may die.

1 Kings 21:13

And there came in two men, children of Belial, and sat before him: and the men of Belial witnessed against him, even against Naboth, in the presence of the people, saying, Naboth did blaspheme God and the king. Then they carried him forth out of the city, and stoned him with stones, so that he died.

Matthew 26:60-61

But found none: yea, though many false witnesses came, yet found they none. At the last came two false witnesses,

Revelation 11:3-7

And I will give power unto my two witnesses, and they shall prophesy a thousand two hundred and three score 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 that is worthy of death be put to death; but at the mouth of one witness he shall not be put to death.
Numbers 35:30
Whoever kills any person, the murderer shall be put to death by the mouth of witnesses: but one witness shall not testify against any person to cause him to die.
1 Kings 21:10
And set two men, sons of Belial, before him, to bear witness against him, saying, You did blaspheme God and the king. And then carry him out, and stone him, that he may die.
Matthew 18:16
But if he will not hear you, then take with you one or two more, that in the mouth of two or three witnesses every word may be established.
Matthew 26:60
But found none: yea, though many false witnesses came, yet found they none. At the last came two false witnesses,
John 8:17
It is also written in your law, that the testimony of two men is true.
2 Corinthians 13:1
This is the third time I am coming to you. In the mouth of two or three witnesses shall every word be established.
1 Timothy 5:19
Against an elder receive not an accusation, unless before two or three witnesses.
Hebrews 10:28
He that despised Moses' law died without mercy under two or three witnesses:
Revelation 11:3
And I will give power unto my two witnesses, and they shall prophesy a thousand two hundred and three score days, clothed in sackcloth.

General references

Numbers 35:30
Whoever kills any person, the murderer shall be put to death by the mouth of witnesses: but one witness shall not testify against any person to cause him to die.
Deuteronomy 17:6
At the mouth of two witnesses, or three witnesses, shall he that is worthy of death be put to death; but at the mouth of one witness he shall not be put to death.
John 7:51
Does our law judge any man, before it hears him, and knows what he does?