Or HaChaim on Leviticus 11:2/אור החיים על ויקרא י״א:ב׳

1 אל בני ישראל לאמור. to the children of Israel saying. The word לאמור here indicates that the legislation following conferred a distinction upon the Israelites who were to keep their distance from matters considered impure. Vayikra Rabbah 13,2 quotes Rabbi Shimon bar Yochai commenting on Chabakuk 3,6: "When He stands He measures the earth;" Rabbi Shimon interprets that G'd measured all the nations and found not one of them deserving to receive the Torah except the generation travelling through the desert. G'd measured all the mountains and the only one fit to hand down the Torah from was Mount Sinai. The word לאמור in this context must be understood along the lines of Isaiah 3,10: אמרו צדיק כי טוב כי פרי מעלליהם יאכלו. "Hail the just man, for he shall fare well; he shall eat the fruit of his works." The sequence of לאמור זאת means that Moses and Aaron are to take every kind of creature into their hands and display them saying: "this you may eat and this you may not eat." It was not enough to instruct the Israelites only orally.

2זאת החיה אשר תאכלו; "these are the living things which you may eat;" I have already explained elsewhere why the term חיה is applied here to domesticated animals בהמה. The term חיה implies that nothing evil adheres to these creatures. This term is used in contradistinction to other domesticated beasts which are not associated with the concept of sanctity at all.