Midrash su Levitico 11:28

8) (Vayikra 11:28): "And he that carries their carcass shall wash his clothes": We are hereby taught that the carrier confers tumah upon (his) clothing. (Without this verse we would say) does it not follow a fortiori (that the carrier does not confer tumah upon his clothing, viz.:) if in an instance — that of touching — where they become tamei of themselves (i.e., when the clothes themselves touch neveilah), they do not become tamei by virtue of the toucher (of the neveilah, who wears them), then how much more so, in an instance where they do not become tamei of themselves — that of carrying — (how much more so) should they not become tamei by virtue of the wearer! It must, therefore, be written that the wearer shall wash his clothes, whereby we are taught that the wearer confers tumah upon (his) clothing.

9) We could reason a fortiori that they (clothes) should not become tamei of themselves by touching (neveilah), viz.: If in an instance where they become tamei through the carrier, they do not become tamei of themselves (by lifting neveilah in a balance scale), then, in an instance where they do not become tamei through the toucher (who wears them), how much more so should they not become tamei of themselves by touching (neveilah)! It is, therefore, written "Everything that touches them will be unclean," both men and implements.

10) We could reason a fortiori that they should become tamei of themselves by carrying (i.e., by lifting neveilah in a balance scale), viz.: If in an instance where they do not become tamei through the toucher (who wears them), they become tamei of themselves by touching (neveilah), then, in an instance where they do become tamei through the carrier (who wears them), how much more so should they become tamei of themselves by carrying (i.e., by lifting neveilah in a balance scale)! It is, therefore, written (Vayikra 11:28): "they are tamei to you," and neither food, nor drink, nor implements become tamei by carrying (neveilah in a scale). It is the carrier (that confers the tumah), and not that which is being carried (the neveilah).