A single witness may not testify against another person for any trespass or sin that he commits. A matter may be legally established only on the testimony of two or three witnesses.
TSK
TSK · Deuteronomy 17:6
Treasury of Scripture Knowledge references in NET.
John 8:17
TSK
It is written in your law that the testimony of two men is true.
1 Timothy 5:19
TSK
Do not accept an accusation against an elder unless it can be confirmed by two or three witnesses.