“the King of Kings hath appeared”

“Ye are but vassals, O kings of the earth! He Who is the King of Kings hath appeared, arrayed in His most wondrous glory, and is summoning you unto Himself, the Help in Peril, the Self-Subsisting. Take heed lest pride deter you from recognizing the Source of Revelation; lest the things of this world shut you out as by a veil from Him Who is the Creator of heaven. Arise, and serve Him Who is the Desire of all nations, Who hath created you through a word from Him, and ordained you to be, for all time, the emblems of His sovereignty. 

- Bahá’u’lláh  (Quoted by Shoghi Effendi, ‘The Promised Day Is Come’)

“The Most Great Law hath been revealed”

And further: “O kings of the earth! The Most Great Law hath been revealed in this Spot, this Scene of transcendent splendor. Every hidden thing hath been brought to light, by virtue of the Will of the Supreme Ordainer, He Who hath ushered in the Last Hour, through Whom the Moon hath been cleft, and every irrevocable decree expounded.” 

- Bahá’u’lláh  (Quoted by Shoghi Effendi, ‘The Promised Day Is Come’) 

“O kings of the earth!... with radiant hearts, lift up your faces unto your Lord, the Lord of all names”

…at a time when the rulers of the earth had definitely forsaken Him [Bahá’u’lláh]—in such a Book [the Kitáb-i-Aqdas] we read the following:

“O kings of the earth! He Who is the sovereign Lord of all is come. The Kingdom is God’s, the omnipotent Protector, the Self-Subsisting. Worship none but God, and, with radiant hearts, lift up your faces unto your Lord, the Lord of all names. This is a Revelation to which whatever ye possess can never be compared, could ye but know it. We see you rejoicing in that which ye have amassed for others, and shutting out yourselves from the worlds which naught except My Guarded Tablet can reckon. The treasures ye have laid up have drawn you far away from your ultimate objective. This ill beseemeth you, could ye but understand it. Wash your hearts from all earthly defilements, and hasten to enter the Kingdom of your Lord, the Creator of earth and heaven, Who caused the world to tremble, and all its peoples to wail, except them that have renounced all things and clung to that which the Hidden Tablet hath ordained....” 

- Bahá’u’lláh  (Quoted by Shoghi Effendi, ‘The Promised Day Is Come’) 

“the Kitáb-i-Aqdas (The Most Holy Book), that priceless treasury enshrining for all time the brightest emanations of the mind of Bahá’u’lláh”

…the Kitáb-i-Aqdas (The Most Holy Book), that priceless treasury enshrining for all time the brightest emanations of the mind of Bahá’u’lláh, the Charter of His World Order, the chief repository of His laws, the Harbinger of His Covenant, the Pivotal Work containing some of His noblest exhortations, weightiest pronouncements, and portentous prophecies, and revealed during the full tide of His tribulations… 

- Shoghi Effendi  (‘The Promised Day Is Come’)

Bahá’u’lláh reminds the “concourse of kings” about His “afflictions” and admonishes them for failing “to stay the hand of the aggressor”

And again in that same Tablet: “Twenty years have passed, O kings, during which We have, each day, tasted the agony of a fresh tribulation. No one of them that were before Us hath endured the things We have endured. Would that ye could perceive it! They that rose up against Us, have put Us to death, have shed Our blood, have plundered Our property, and violated Our honor. Though aware of most of Our afflictions, ye, nevertheless, have failed to stay the hand of the aggressor. For is it not your clear duty to restrain the tyranny of the oppressor, and to deal equitably with your subjects, that your high sense of justice may be fully demonstrated to all mankind?

“God hath committed into your hands the reins of the government of the people, that ye may rule with justice over them, safeguard the rights of the downtrodden, and punish the wrongdoers. If ye neglect the duty prescribed unto you by God in His Book, your names shall be numbered with those of the unjust in His sight. Grievous, indeed, will be your error. Cleave ye to that which your imaginations have devised, and cast behind your backs the commandments of God, the Most Exalted, the Inaccessible, the All-Compelling, the Almighty? Cast away the things ye possess, and cling to that which God hath bidden you observe. Seek ye His grace, for he that seeketh it treadeth His straight Path.

Bahá’u’lláh reminds the “concourse of kings” where their "true and abiding glory reside"

What is it of which ye can rightly boast? Is it on your food and your drink that ye pride yourselves, on the riches ye lay up in your treasuries, on the diversity and the cost of the ornaments with which ye deck yourselves? If true glory were to consist in the possession of such perishable things, then the earth on which ye walk must needs vaunt itself over you, because it supplieth you, and bestoweth upon you, these very things, by the decree of the Almighty. In its bowels are contained, according to what God hath ordained, all that ye possess. From it, as a sign of His mercy, ye derive your riches. Behold then your state, the thing in which ye glory! Would that ye could perceive it! Nay! By Him Who holdeth in His grasp the kingdom of the entire creation! Nowhere doth your true and abiding glory reside except in your firm adherence unto the precepts of God, your wholehearted observance of His laws, your resolution to see that they do not remain unenforced, and to pursue steadfastly the right course....” 

- Baha’u’llah  (Quoted by Shoghi Effendi, ‘The Promised Day Is Come’)