Remembrance is a powerful support on the path to God (Glorious and Majestic). Indeed, it is the very foundation of this Sufi path. No one reaches God save by continual remembrance of Him. There are two kinds of remembrance: that of the tongue and that of the heart. The servant attains perpetual remembrance of the heart by making vocal remembrance. It is remembrance of the heart, however, that yields true effect. When a person makes remembrance with his tongue and his heart simultaneously, he attains perfection in his wayfaring. –Al-Qushayri, Al RisalahRegarding the practice you mentioned, one should vocalize out loud for an hour. You can perform mental recitation afterward if you choose.
For thirty years I sought God. But when I looked carefully I found that in reality God was the seeker and I the sought. -Bayazid al-Bastami
Books for Prisons