The mystic and theologian Sahl al-Tustari (c.818-896 CE) was born in the fortress town of Tustar in southwestern Persia.  It is said that when he was very young, only three years old, he used to waken in the night to find his uncle Muhammed deep in prayer and contemplation. Feeling something in his heart at that moment, the boy asked his uncle if he could be like him.  Muhammed replied, “You are still young.  Suffice it that you remember Allah Who created you.”

“How shall I remember Him?”

“Say in your heart, whenever you are alone in the night, three times without moving your tongue:
Allah is with me;
Allah is looking at me;
Allah is witnessing me.

“When you feel strengthened by it, increase it to seven times.  That will be a great help to you, for if you know that Allah is with you, and is looking at you, and is witnessing what you do, surely you will not do anything that will displease Him.”

Sahl took this as his practice, increasing it from three to seven to eleven repetitions and then to many more, and it was a lifelong attunement for him.  In later life, he developed into a great Sufi, wrote a profound commentary on the inner and outer meaning of the Koran, and was one of the teachers of the well-known Sufi martyr Mansur al-Hallaj.