Testify against him that which is wrong - Margin, more literally, "a falling away." The word is used Deuteronomy 13:5 to signify apostasy or revolt; here it is no doubt to be understood in the wider sense of any departure from the Law.

If a false witness rise up against any man,.... In a court of judicature:

to testify against him: that which is not true of him, let it be in what case it will; Aben Ezra instances in idolatry, but it holds good of any other.

If a false witness rise up against any man to testify against him that which is wrong;

19:16 A safe witness - A single witness, though he speak truth, is not to be accepted for the condemnation of another man, but if he be convicted of false witness, this is sufficient for his own condemnation.

that...: or, falling away

De 19:16-21. Punishment of a False Witness.

16-21. But if convicted of perjury, it will be sufficient for his own condemnation, and his punishment shall be exactly the same as would have overtaken the object of his malignant prosecution. (See on [158]Ex 21:23; see also Le 24:20).

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.