Midrash sur Le Lévitique 11:45

4) "and you shall not make yourselves tamei with every creeping thing that creeps upon the earth": even if it does not reproduce. (Vayikra 11:45): "For I am the L–rd, who brought you up out of the land of Egypt": It is for this reason that I brought you up out of the land of Egypt, on condition that you accept upon yourselves the yoke of mitzvoth. For all who accept the yoke of mitzvoth acknowledge the exodus from Egypt, and all who do not accept the yoke of mitzvoth deny the exodus from Egypt. "to be a G d to you" — perforce! "And you shall be holy, for I am holy.": Just as I am holy, so you are holy. Just as I am divorced (from the material), so, you, divorce yourselves (from materialism).