If a man lie with a beast,.... A sin quite unnatural, exceeding shocking and detestable, forbid Leviticus 18:23,
he shall surely be put to death: by stoning, as the Targum of Jonathan adds; and this is the death such are condemned to in the Misnah (h):
and ye shall slay the beast; with clubs, as says the Targum of Jonathan; the reasons given in the Misnah (i), why the beast was to be slain, are, because ruin came to the man by means of it, and that it might not be said, as it passed along the streets, that is the beast for which such an one was stoned. Aben Ezra says it was to be slain, that it might not cause others to sin; and he adds, there are that say it was to cover the reproach: no doubt the true reason was to deter the more from this detestable sin, that if a beast, which was only accessory to it, and an instrument of it, was put to death, of how much sorer punishment must the man that committed it be worthy of, even of eternal wrath and destruction, and, unless repented of and forgiven, must be expected by him?
(h) Misn. Sanhedrin, c. 7. sect. 4. (i) Ibid.

Slay the beast - Partly for the prevention of monstrous births, partly to blot out the memory of so loathsome a crime.