What follows is my provisional translation (in other words, not official or authorized; see here for more) of an Arabic prayer for protection by Bahá’u’lláh. The original Arabic text has been published in Majmúʻiy-i-Alváḥ-i-Mubárakih, p. 275.
Shortly after producing this provisional translation, I was informed that an authorized translation of it had previously been prepared on behalf of the Universal House of Justice in 1996, which can be found online here. It is also available on the Baháʼí Reference Library here.
In His Name, the Most Exalted, the Inaccessible, the Most High
Lauded be Thy Name, O Thou Who art my God and my Master, my Lord and my Mainstay, my Hope and my Refuge, my Light and my Splendor! I beseech Thee by Thy hidden, Thy treasured Name—which none but Thine own Self knoweth—to shelter the bearer of this scroll from every affliction and plague, to keep him safe from every fiendish man and woman, to shield him from the wickedness of the ungodly, and to guard him against the schemes of the infidels. Protect him also, O my God, from every ache and pain, O Thou in Whose hands is the kingdom of all things! Thou, indeed, hast power over all things. Thou doest as Thou willest, and ordainest as Thou pleasest.
O King of Kings! O Ruler of every compassionate one! O Thou Whose beneficence is preexistent! O Bestower of gifts and favors! O Thou Who healest every sickness, and art sufficient unto the distressed! O Light of lights, the Light above all other lights! O Thou Who revealest every Revelation! O Thou the Most Merciful, the Most Compassionate! Have mercy upon the bearer of this scroll, by Thy supreme clemency and Thine abounding munificence, O Thou the Generous, the Bountiful. Guard him, moreover, with Thy protection, against whatsoever is abhorrent unto his heart. Of them that possess power, Thou, verily, art the Most Powerful.
The glory of God rest upon thee, O resplendent sun! Bear thou witness to that whereunto God hath testified unto Himself: Verily, there is none other God but Him, the Almighty, the Best-Beloved.
The complete Arabic text of this prayer appears below in typed form.