15 One witness shall not rise up against a man for any iniquity, and for any sin, in any sin that he sinneth: at the mouth of two witnesses, or at the mouth of three witnesses, shall a matter be established. 16 If an unrighteous witness rise up against any man to testify against him of an offence; 17 then both the men between whom the controversy is shall stand before Jehovah, before the priests and the judges that shall be in those days; 18 and the judges shall make thorough inquiry; and if the witness be a false witness, and he have testified falsely against his brother, 19 then shall ye do unto him as he had thought to have done unto his brother; and thou shalt put evil away from thy midst.
Matthew Henry's Commentary on Deuteronomy 19:15-19
Commentary on Deuteronomy 19:15-21
(Read Deuteronomy 19:15-21)
Sentence should never be passed upon the testimony of one witness alone. A false witness should suffer the same punishment which he sought to have inflicted upon the person he accused. Nor could any law be more just. Let all Christians not only be cautious in bearing witness in public, but be careful not to join in private slanders; and let all whose consciences accuse them of crime, without delay flee for refuge to the hope set before them in Jesus Christ.