Deuteronomy 17:7

7.The hands of the witnesses shall be first. It was not without reason that God would have criminals put to death by the hand of those by whose testimony they were condemned. The ancient people did not employ public executioners, that there might be more solemnity, modesty, and reverence in the infliction of punishments. This office he peculiarly enjoins upon the witnesses, because the tongue of many is too hasty, not to say worse of it, so that they do not hesitate to stab people verbally, when they would not dare to lay a finger upon them. This, then, was an excellent remedy for the repression of light accusations, not to admit the testimony of any, whose hand was not prepared to execute the sentence. Stoning was indeed a sad and horrible kind of punishment; but it is probable that God made choice of it because it required the application of many hands. If hanging had not been in use, God would have commanded in vain that the corpse of a man who had been hanged should be taken down from the tree before sunset. (Deuteronomy 21:23.) There were, therefore, other kinds of capital punishment; but when the land was to be purged, as by a propitiation, by the death of the sinner, he was to be stoned by the hands of the whole people, since it would have been cruel for him to be slain by a lingering death, which would have been the case if they had stoned him one after another. The reason why the people were commanded to cast the stones with one consent was, that they might give proof of their zeal, and manifest their great indignation that God’s worship had been violated.