Leviticus 24:14
Bring forth him that hath cursed without the camp; and let all that heard him lay their hands upon his head, and let all the congregation stone him. Bring forth him that hath cursed without the camp; and let all that heard him lay their hands upon his head, and let all the congregation stone him.
The one who had uttered the curse was to be brought outside the camp to be punished. Those who had heard him were to lay their hands upon his head, solemnly testifying thereby that the charge against him was true. Then the whole congregation was to stone him.