Tertullian, De Virginibus Velandis, cap. 17. Hottentot women, also (Fritsch, Eingeborene Südafrika's, p. 311), cover their head with a cloth, and will not be persuaded to remove it.
Wellhausen, Reste Arabischen Heidentums, p. 196. The same custom is found among Tuareg men though it is not imperative for the women (Duveyrier, Les Touaregs du Nord, p. 291).
Quoted in Zentralblatt für Anthropologie, 1906, Heft I, p. 21.
Or rather, perhaps, because the sight of their nakedness might lead the angels into sin. See W. G. Sumner, Folkways, p. 431.