Or HaChaim on Leviticus 11:44/אור החיים על ויקרא י״א:מ״ד

1 כי אני ה׳ אלוקיכם, "for I am the Lord your G'd." The major difference between Israel and any other nation is that G'd has not described Himself as the "Lord G'd" of any other nation. This obligates us to keep our distance from anything which contaminates us.

2והתקדשתם והייתם קדושים, "sanctify yourselves and be holy." The meaning of this statement is that if we do our share in trying to deserve the appellation "holy," G'd on His part will bestow such a title upon us by not allowing such contaminating elements to enter our bodies. We have already quoted the Talmud Chulin 4 in which G'd is described as insuring that even the beasts of the righteous do not eat matters unfit for the owner to eat. G'd would certainly protect the צדיק himself against erroneously consuming such matters.

3Another meaning of the word והתקדשתם is "sanctify yourselves by means of erecting protective legal fences," i.e. rabbinic ordinances designed to reduce the likelihood of contacting and absorbing impure material. G'd tells us that if you do this: "I in turn will help you become holy." The Torah then spells out in what respect you are going to be holy. כי קדוש אני, "for I am holy;" G'd made His presence amongst us dependent on our keeping ourselves apart from contaminating influences. This is why such people are entitled to the same appellation "holy" as is applied to G'd Himself. ולא תטמאו "and you will not become defiled, etc." This is a promise by G'd that if we make every effort not to become contaminated by the שרצים ושקצים swarming detestable things mentioned in this chapter, G'd's appreciation will become manifest in that we will not become the passive victims of other kinds of impurity. Pagans are included in the terminology שרצים ושקצים. G'd promises that if we make every effort not to become contaminated by the swarming or creeping things mentioned in this chapter, He will make sure that we will not be under the dominion of pagans.