The lowest level of remembrance is just of the tounge.But when the remembrance reaches ones heart,it becomes the remembrance of the heart this will become the remembrance of the spirit. The station of witnessing without limit, without end, and you witness God as if He is in front of you all the time. This is the remembrance of the perfected ones.
The truth of adh-dhikr reaches the point of stopping the mentioning of God, as you become immersed in the ocean of the presence and there is no speaking. You are witnessing God, and there is no need to call for Him. As when you travel, you need a vehicle to get there, but when you reach, you no longer need it. This does not mean that you throw away your vehicle; you keep it all the time. You remember in everything now, in your heart, your tongue, your hands, in everything. This is the unlimited witnessing. You hear Allah in everything, and in every voice. You hear the dhikr in the voices of the animals, in every song of every bird, and in everything. This is the station of witnessing and of freedom , and this is the real remembrance.