Deuteronomy 17:6
At the mouth of two witnesses, or three witnesses, shall he who is to die be put to death. He shall not be put to death at the mouth of one witness.
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 so that he dies.
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.
Matthew 18:16
But if he should not hear, take with thee one or two besides, so that at the mouth of two or three witnesses every word may be established.
2 Corinthians 13:1
This third time I am coming to you. In the mouth of two witnesses or three every saying will be confirmed.
1 Timothy 5:19
Accept no accusation against an elder, except at two or three witnesses.
Hebrews 10:28
Any man who has disregarded the law of Moses dies without mercies from two or three witnesses.
John 8:17-18
And also it is written in your law that the testimony of two men is valid.