The New John Gill Exposition of the Entire BibleLeviticus 11:31
These are unclean to you of all that creep…
food, and not to be touched, at least when dead, as in the next clause,
that is, these eight sorts of creeping things before mentioned, as the
Targum of Jonathan expresses it, and these only, as Maimonides says
whosoever doth touch them when they are dead shall be unclean until
for touching them while alive did not defile, only when
dead; and this the Jews interpret, while they are in the case in which
they died, that is, while they are moist; for, as Ben Gersom says, if
they are so dry, as that they cannot return to their moisture, they do
not defile; for which reason, neither the bones, nor nails, nor nerves,
nor skin of these creeping things, defile; but, they say F19, while the
back bone is whole, and the bones cleave to it, then a creeping thing
is reckoned moist, and while it is so it defiles.
F18 Hilchot, Abot Hatumaot, c. 4. sect. 14.
F19 Maimon. & Bartenora in Misn. Niddah, c. 7. sect. 1.