In Farid al-Din Attar's The Conference of the Birds, the anecdote of the Creator's address to Prophet David conveys a core Sufi theological doctrine: Divine irreplaceability. The poem states that every created thing, whether good or bad, visible or hidden, has a substitute or equal, except for God. Consequently, God demands that the soul remain wholly attached to Him alone, as He is the only indispensable necessity for spiritual survival, and no worldly entity can ever fill His place.