Deuteronomy 17:5-7

5take the man or woman who has done this evil deed to your city gate and stone that person to death. 6On the testimony of two or three witnesses a person is to be put to death, but no one is to be put to death on the testimony of only one witness.

7The hands of the witnesses must be the first in putting that person to death, and then the hands of all the people. You must purge the evil from among you.