In Section 19 of Jami's Haft Awrang, the poet highlights a unique phonetic feature of the Islamic declaration of faith, La ilaha illallah: none of its letters are labial (شفوی), meaning it can be recited without any visible movement of the lips. Jami interprets this linguistic characteristic as a divine allusion to the necessity of 'hidden remembrance' (dhikr-e khafi). Because the phrase can be uttered silently in the heart without physical signs of speech, it perfectly facilitates a private, inward devotion that is concealed from others and free from ostentation.