Is it permissible to wipe over an outer sock after having wiped over the inner sock beneath it, and then to nullify one's ablution?

It is permissible to wipe over the second sock if it was worn over a sock that had already been wiped over, because it was worn in a state of ritual purity (taharah). Thus, it falls under the general meaning of the noble Hadith: "Leave them, for I inserted them while they were pure," so he wiped over them. Some scholars consider this a strong opinion, because wiping over the khuffs (leather socks) removes the ritual impurity (hadath), meaning the second sock was worn in a state of complete purity. However, if the second sock was worn while one was in a state of ritual impurity, then it is not permissible to wipe over it.