In Islamic law, the use of hadith as now understood (hadith of Muhammad with documentation, isnads, etc.) came gradually. According to scholars such as Joseph Schacht, Ignaz Goldziher, and Daniel W. Brown, early schools of Islamic jurisprudence used rulings of the Prophet's Companions, the rulings of the Caliphs, and practices that “had gained general acceptance among the jurists of that school”. On his deathbed, Caliph Umar instructed Muslims to seek guidance from the Quran, the early Muslims ("muhajirun") who emigrated to Medina with Muhammad, the Medina residents who welcomed and supported the "muhajirun" (the "ansar"), the people of the desert, and the protected communities of Jews and Christians ("ahl al-dhimma").