Umm Salama said that she asked God's Messenger whether a woman might pray in a shift and veil without wearing a lower garment. He replied, “If the shift is ample and covers the surface of her feet.”
Abu Dawud transmitted it and he mentioned a number who did not trace it beyond Umm Salama.
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.