Deuteronomy 17:5-7

Young's Literal Translation

⁵ `Then thou hast brought out that man, or that woman, who hath done this evil thing, unto thy gates -- the man or the woman -- and thou hast stoned them with stones, and they have died.

⁶ By the mouth of two witnesses or of three witnesses is he who is dead put to death; he is not put to death by the mouth of one witness;

⁷ the hand of the witnesses is on him, in the first place, to put him to death, and the hand of all the people last; and thou hast put away the evil thing out of thy midst.