Mishkat al-Masabih #714

Shaddad b. Aus reported God’s Messenger as saying, “Act differently from the Jews, for they do not pray in their sandals or their shoes.”* * Khuff (pl. khifaf), an article of footwear which came up above the ankle. Traditions tell that the Prophet allowed pilgrims to wear the khuff only when unable to procure sandals, but said they must be cut to come below the ankle. Cf. Bukhari, Hajj, 21, 23; Libas, 8, 4, 15, 73. Abu Dawud transmitted it.