In Farid ud-Din Attar's 'Discourse of a Sufi with a Man Who Had Lost His Key' from The Conference of the Birds, the act of sitting patiently at a closed door serves as an allegory for spiritual perseverance and reliance on Divine grace. The Sufi advises the seeker that even without the 'key' of his own devices or intellect, simply remaining steadfast at the threshold of the Divine will ensure that the door is eventually opened for him. This emphasizes the Sufi principle that persistent devotion and patience are essential, and that spiritual openings ultimately come from God rather than human effort.