Inner sin according to Said Ramadan Al-Bouti

The sin within:

Every Muslim knows that works are accepted and acceptable only by the good intentions that motivate them. But how many draw the consequences; how many see what this implies in the work they do on themselves to give meaning to their daily practices and to ensure that nothing inwardly taints their good deeds? The heart of Islam is touched there. And the heart of the reader challenged! What is Islam in essence? And if we conform to it in appearance, do we conform to it heart and soul? The author tackles all these points by coming back to the notion of Sufism, to describe its founded part and to define its true borders, in the light of the Koran and the Sunna; and especially to affirm with force that the denominations do not matter if one sticks to what is true and certain.