Deuteronomy 13:9-11

Thou shalt surely kill him Not privately, a permission to do which, under pretence of the party's being guilty of the crime in question, would have opened the door to innumerable murders; but by procuring his death through the sentence of the magistrate. Thy hand shall be first upon him As the witness of his crime; for he was to be stoned to death, and the accuser was to throw the first stone, together with the witnesses, Deuteronomy 17:7. This law, at first sight, may appear too great a trial to humanity; but it is indeed no more than requiring a compliance with that plain principle of religion and morality, to sacrifice all private considerations to the glory of God and good of mankind. All Israel shall hear and fear The law, though severe, yet was just and necessary, and calculated to preserve the body of the people from the contagion of idolatry.