" Degrees of superiority are also implied by the Revelation in its mention of the heart. In speaking of the majority, it says: ‘Not blind are the eyes, but blind are the hearts within the breasts.’ The Prophet on the other hand, like Prophets before him, said that his heart was awake, which means that its eye was open; and the Koran indicates that this possibility can be shared, if only in some measure, by others also, for it sometimes addresses itself directly to ‘those who have hearts.’ It is reported that of Abu Bakr the Prophet said: “He surpasseth you not through much fasting and prayer but he surpasseth you in virtue of something that is fixed in his heart. "

― , Muhammad: His Life Based on the Earliest Sources