“A just king is the shadow of God on earth.”

In the Lawḥ-i-Sulṭán Bahá’u’lláh further reveals the significance of kingship: “A just king is the shadow of God on earth. All should seek shelter under the shadow of his justice, and rest in the shade of his favor. This is not a matter which is either specific or limited in its scope, that it might be restricted to one or another person, inasmuch as the shadow telleth of the One Who casteth it. God, glorified be His remembrance, hath called Himself the Lord of the worlds, for He hath nurtured and still nurtureth everyone. Glorified be, then, His grace that hath preceded all created things, and His mercy that hath surpassed the worlds.” 

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

“the king who will arise to aid My Cause in My Kingdom”: - “is the very eye of mankind, the luminous ornament on the brow of creation, the fountainhead of blessings unto the whole world”

In the Kitáb-i-Aqdas He sets forth His purpose, and eulogizes the king who will profess His Faith: “By the Righteousness of God! It is not Our wish to lay hands on your kingdoms. Our mission is to seize and possess the hearts of men. Upon them the eyes of Bahá are fastened. To this testifieth the Kingdom of Names, could ye but comprehend it. Whoso followeth his Lord, will renounce the world and all that is therein; how much greater, then, must be the detachment of Him Who holdeth so august a station!” “How great the blessedness that awaiteth the king who will arise to aid My Cause in My Kingdom, who will detach himself from all else but Me! Such a king is numbered with the Companions of the Crimson Ark—the Ark which God hath prepared for the people of Bahá. All must glorify his name, must reverence his station, and aid him to unlock the cities with the keys of My Name, the Omnipotent Protector of all that inhabit the visible and invisible kingdoms. Such a king is the very eye of mankind, the luminous ornament on the brow of creation, the fountainhead of blessings unto the whole world. Offer up, O people of Bahá, your substance, nay your very lives, for his assistance.” 

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