"Once in about a thousand years shall this City be renewed and re-adorned."

"They that valiantly labour in quest of God’s will, when once they have renounced all else but Him, will be so attached and wedded to that City that a moment’s separation from it would to them be unthinkable. They will hearken unto infallible proofs from the Hyacinth of that assembly, and receive the surest testimonies from the beauty of its Rose and the melody of its Nightingale. Once in about a thousand years shall this City be renewed and re-adorned.

Wherefore, O my friend, it behooveth Us to exert the highest endeavour to attain unto that City, and, by the grace of God and His loving-kindness, rend asunder the “veils of glory”; so that, with inflexible steadfastness, we may sacrifice our drooping souls in the path of the New Beloved. We should with tearful eyes, fervently and repeatedly, implore Him to grant us the favour of that grace. That city is none other than the Word of God revealed in every age and dispensation. In the days of Moses it was the Pentateuch; in the days of Jesus the Gospel; in the days of Muḥammad the Messenger of God the Qur’án; in this day the Bayán; and in the dispensation of Him Whom God will make manifest His own Book—the Book unto which all the Books of former Dispensations must needs be referred, the Book which standeth amongst them all transcendent and supreme. In these cities spiritual sustenance is bountifully provided, and incorruptible delights have been ordained. The food they bestow is the bread of heaven, and the Spirit they impart is God’s imperishable blessing. Upon detached souls they bestow the gift of Unity, enrich the destitute, and offer the cup of knowledge unto them who wander in the wilderness of ignorance. All the guidance, the blessings, the learning, the understanding, the faith, and certitude, conferred upon all that is in heaven and on earth, are hidden and treasured within these Cities."

-Bahá'u'lláh, The Kitáb-i-Íqán, pp. 198-200