Deuteronomy 19:15

15 A single witness shall not suffice to convict a person of any crime or wrongdoing in connection with any offense that may be committed. Only on the evidence of two or three witnesses shall a charge be sustained.

Deuteronomy 19:15 Meaning and Commentary

Deuteronomy 19:15

One witness shall not rise up against a man for any iniquity,
or for any sin, in any sin that he sinneth
Whether capital sins, or pecuniary debts; or whatsoever sins a man may be guilty of whether sins against the first or second table of the law, whether greater or lesser sins, whether in moral or civil things; the Jews except only in the case of a woman suspected of adultery and of beheading the heifer:

at the mouth of two witnesses, or at the mouth of three witnesses,
shall the matter be established;
either for acquittance or condemnation; and the witnesses may not, as Jarchi says, write their testimony in a letter, and send it to the sanhedrim, nor may an interpreter stand between the witnesses and the judges; (See Gill on Deuteronomy 17:6).

Deuteronomy 19:15 In-Context

13 Show no pity; you shall purge the guilt of innocent blood from Israel, so that it may go well with you.
14 You must not move your neighbor's boundary marker, set up by former generations, on the property that will be allotted to you in the land that the Lord your God is giving you to possess.
15 A single witness shall not suffice to convict a person of any crime or wrongdoing in connection with any offense that may be committed. Only on the evidence of two or three witnesses shall a charge be sustained.
16 If a malicious witness comes forward to accuse someone of wrongdoing,
17 then both parties to the dispute shall appear before the Lord, before the priests and the judges who are in office in those days,
New Revised Standard Version Bible, copyright 1989, Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved.