At the bottom of the lower part of the body we find the foot, the lowest limb, which is therefore particularly sensitive. The Haredim have a body of knowledge concerning the foot of God.
Written By Professor Gideon Aran
There are restrictions regarding feet, and limitations on their exposure. Haredim keep their shoes on in circumstances in which others would take them off; and where others would go barefoot, Haredim will not remove their socks. Indeed, it is not uncommon to see Haredim in the park walking around on the grass or sand in their socks. Even at home, among family, the Haredi foot is not to be seen.
Haredim have been observed carrying out curative exercises (with special rabbinical permission), such as jumping on an exercise mat, with their socks on; some of them don’t even remove their shoes.
There is a special prohibition against touching feet, even for a medicinal massage or casual rubbing. There are strict Haredim who even go to bed with their socks on. They believe that exposed feet are an especially grave matter at night, as they might be overrun by demonic powers.
Taken from “Denial Does Not Make The Haredi Body Go Away Ethnography of a Disappearing (?) Jewish Phenomenon”, By Gideon Aran.