Midrash su Levitico 11:43

1) (Vayikra 11:29-31): "And this to you is what is unclean among the creeping things (sheratzim) which creep upon the earth: the weasel and the mouse, and the great lizard after its kind. And the gecko, and the land-crocodile, and the lizard, and the sand lizard, and the chameleon. These are what are unclean to you among all that creep." What is the intent of this? Because it is written (Vayikra 11:43): "Do not make yourselves tamei by them (sheratzim) and you will become tamei through them," I might think that inner-body tumah and the tumah of offerings are being spoken of; it is, therefore, written "And this (i.e., only this to you is what is unclean … the weasel and the mouse, and the great lizard, after its kind, etc." I might think that these confer tumah on men and implements and the others confer tumah on men but not on implements, or on implements but not on men; it is, therefore written (Vayikra 11:31): "These (are what are unclean to you"). Only these (confer tumah). Or, perhaps only these are excluded which are like the particular (kinds mentioned here, viz.:) Just as the particular have bones and reproduce, so, only those are excluded which have bones and reproduce. Whence do we derive (that also excluded are) those which have bones and do not reproduce or those which do not have bones and reproduce? From "These" are tamei to you among all that creep" — Only these among the sheratzim confer tumah.

Resh Lakish said: "What is the meaning of the passage (Prov. 3, 34) If [it concerns] the mockers He will mock, but to the modest He will give grace; i.e., if one wishes to defile himself [with sin] the door is merely opened to him; but if one comes to purify himself, he is assisted." In the house of learning of R. Ishmael it was taught: "This statement may be compared to the story of a merchant who sells both naphtha and perfumes (Fol. 39); when one arrives to buy naphtha, he saith to him: 'Measure yourself the quantity you need'; but if one arrives to buy perfumes, he says, 'Wait, we will both measure it, so that I may also inhale the odor.'" The same disciples taught: "Sin dulls the heart of a man, as it is said (Lev. 11, 43) And ye shall not make yourselves unclean with them, that ye should he defiled thereby. Read not V'nitmethem (you will be defiled), but Untamatam (you will become dull-hearted)." Our Rabbis were taught: The passage, And ye shall not make yourselves unclean with them, that ye should be defiled, implies that, when a man defiles himself, a little, he will become defiled much; [when one defiles himself] here below he will be defiled from above; and when [he defiles himself] in this world, he will be defiled in the world to come. Our Rabbis have been taught: Ye shall sanctify yourselves; and be holy. When a man sanctifies himself a little here below, he will be sanstified much above; and when he sanctifies himself in this world, he will be sanctified in the world to come.

3) (Vayikra 11:43): "Do not make your souls detestable by (eating) every creeping thing that creeps" (Vayikra 11:41): "upon the earth": to include (for liability) sheratzim that separated (from the host to the earth) and returned (to the host). (Vayikra 11:43): "and you shall not be tamei by (eating) them": This tells me only of stringent tumah (i.e., that he does not confer tumah upon men and vessels. Whence is it derived that he does sustain the lesser tumah of himself becoming tamei? From (Vayikra 11:43): "and you will be rendered tamei through them." I might think that their blood and their fats are like them (to render the eater tamei); it is, therefore, written "through them," and not through their blood and their fats. "And you shall not become tamei with them, and you will be rendered tamei through them" — If you make yourselves tamei with them, your end will be to have been rendered tamei through them. (Vayikra 11:44) "For I am the L–rd your G d. And you shall make yourselves holy and you shall be holy, for I am holy." Just as I am holy, so are you holy. Just as I am divorced (from the material), so, you, divorce yourselves (from materialism).