Ibn Ishaq, Sirat Rasul Allah in A. Guillaume, trans. and ed., The Life of Muhammad (London, 1955), p. 232
858
Watt, Muhammad at Medina, pp. 6–8; Bamyeh, Social Origins of Islam, pp. 198–99; Marshall G. S. Hodgson, The Venture of Islam: Conscience and History in a World Civilization, 3 vols (Chicago and London, 1974), 1, pp. 75–76
