“The undying Fire which the Lord of the Kingdom hath kindled in the midst of the holy Tree is burning fiercely in the midmost heart of the world. The conflagration it will provoke will envelop the whole earth."

 
"In connection with the Manifestations destined to follow the Revelation of Bahá’u’lláh, ‘Abdu’l‑Bahá makes this definite and weighty declaration: “Concerning the Manifestations that will come down in the future ‘in the shadows of the clouds,’ know verily that in so far as their relation to the source of their inspiration is concerned they are under the shadow of the Ancient Beauty. In their relation, however, to the age in which they appear, each and every one of them ‘doeth whatsoever He willeth.’”

 
“O my friend!” He thus addresses in one of His Tablets a man of recognized authority and standing, “The undying Fire which the Lord of the Kingdom hath kindled in the midst of the holy Tree is burning fiercely in the midmost heart of the world. The conflagration it will provoke will envelop the whole earth. Its blazing flames will illuminate its peoples and kindreds. All the signs have been revealed; every prophetic allusion hath been manifested. Whatever hath been enshrined in all the Scriptures of the past hath been made evident. To doubt or hesitate is no more possible… Time is pressing. The Divine Charger is impatient, and can tarry no longer. Ours is the duty to rush forward and, ere it is too late, win the victory.” And finally, is this most stirring passage which He, in one of His moments of exultation, was moved to address to one of His most trusted and eminent followers in the earliest days of His ministry: “What more shall I say? What else can my pen recount? So loud is the call that reverberates from the Abhá Kingdom that mortal ears are well-nigh deafened with its vibrations. The whole creation, methinks, is being disrupted and is bursting asunder through the shattering influence of the Divine summons issued from the throne of glory. More than this I cannot write.”

'Abdu'l-Bahá cited by Shoghi Effendi

(The World Order of Bahá’u’lláh)
www.bahai.org/r/033185571