In Arabic, the term for remembrance means both repetition and remembrance. The remembrance of the tongue is the beginning and is often just mechanical repetition. As the meaning and power of the words repeated begin to sink in, hearts become filled with joy, longing for God, and other spiritual feelings. This state is the remembrance of the heart. Longing for God is also a sign of God's Presence within. Longing itself is a sign of God's Presence. This state is the remembrance of the soul.

The Prophet said,

God has made a polish for everything that tarnishes.
And the polish for the heart is remembrance.

James Fadiman, Robert Frager, Essential Sufism by James Fadiman, editor, Robert Frager, editor