The realization of 'La ilaha illa Allah' is one of the states of the heart that can be neither expressed by the tongue nor thought out by the mind.
Ibn Ata AllahThe reality of the invocation is when the Invoked takes possession of the heart, and He is One. Separation and multiplicity exist before that for as long as the invoker is in the station of invoking with the tongue or with the heart.
Ibn Ata Allah