R. Shimon says: I might think that just as being the active or passive agent of sodomy renders an animal unfit as an offering, so it renders a Cohein unfit to offer a sacrifice; it is, therefore, written "for it is the abomination of the L-rd your G-d" — the reference is to the sacrifice, and not to the sacrificer.
(Devarim 17:2) "If there be found in your midst, in one of your cities (lit., "gates") which the L-rd your G-d gives you, a man or a woman who would do what is evil in the eyes of the L-rd your G-d, to break His covenant": "If there be found": by witnesses, it being written (Ibid. 19:15) "By word of two witnesses, or by word of three witnesses, shall a thing be established." This is a prototype for the rule that wherever "there be found" is mentioned, Scripture speaks of ("finding") by two or three witnesses.