The following quotations are from:
Al-Ghazzali, On Listening to Music. Trans. Muhammad Nur Abdus Salam, Great Books of the Islamic World, 2002.
“[M]usic does not bring anything to the heart that is not there; instead, it excites what is already in it.” 6
“Those sublime states which begin to attach to them from the invisible world because of the music are called ‘Ecstasy.’ It may happen that their hearts become as cleansed and purified as silver which is placed in fire. That music throws the fire into the heart and removes its tarnishings. It may be that that which is attained through music not be attained with much self-discipline. And music activates that mystery of the relationship which is between a human being and the world of spirits until it becomes possible for him to receive everything from that world so that he becomes unaware of all that there is in this world.” 11
“The first degree is the disciple whose states vary in in the search and traversing of his path from grasping and letting go, ease and difficulty, and the indications of acceptance and the indications of rejection. His whole heart may have become occupied with that. When he hears words in which there is talk of rebuke and acceptance, union and separation, proximity and distance, satisfaction and discontent, hope and hopelessness, security and fear, keeping one’s word and breaking it, the happiness of attainment and the sorrow of separation—and things of this sort—he applies them to his own states. That which is inside him catches fire. Different states appear in him and he falls into various thoughts.” 20-21
“The second degree is that when one has passed the level of the disciples and puts the states and preliminaries behind him, he will have reached the end of that state which is called ‘annihilation’ or ‘non-existence’ when applied to everything save God. When applied to God it is called ‘the Unity’ and ‘Oneness.’ The listening to music of this person is not in the way of understanding sublime reality: rather, when the music touches him, that state of non-existence and one-ness is renewed; he becomes completely absent from himself and unaware of this world. He might, for example, fall into a fire and not realize it: just as Shaykh Abu al-Hasan Nuri, may God have mercy upon him, danced during the music to the place where reeds were cut from a field. His feet were all cut up and slashed, but he was unaware of it. His dance was more fulfilling.
However, the dance of the disciples is mixed with the attributes of humanity. This is that he takes himself back in its entirety from himself; as weas the case with the women when they saw Joseph. They all forgot themselves and cut their hands. You should not deny this non-existence and (as a result) say: ‘I see him. How has he become non-existent?’ That which you see is not he! For you will still see that person when he dies, but he has become non-existent. The truth is that that reality is sublime, at the level of gnosis. But since the knowledge eof all things has left him; everything has become nothing for him. Since he is also unaware of himself, with respect to himself he has become non-existent and nothing remains save the remembrance of God Most High. Everything that was perishable has departed; the eternal remains.
Therefore, the meaning of oneness is that since one sees naught but God Most High, one says: ‘The self is all He and I am not.’ Or one says: ‘I myself am He!’” 22
“Ecstasy is finding. That means that one has found a state which he has not had before.” 23