13. Muhammad ibn al-Hasan ibn Ahmad ibn al-Walid said: Muhammad ibn al-Hasan al-Saffar reported, on the authority of Ahmad ibn Abu `Abdillah al-Barqi on the authority of al-Husayn ibn Sayf, on the authority of his brother `Ali, on the authority of al-Mufaddal ibn Salih on the authority of `Ubayd ibn Zurarah that Abu `Abdillah said: “The statement `There is no god but Allah’ is the price of Heaven.”