What follows is my provisional translation (in other words, not official or authorized; see here for more) of a prayer from Baháʼuʼlláh. The original text has been published in Adʻíyyiy-i-Ḥaḍrat-i-Maḥbúb, pp. 365–368.
Call thou, with the voice of thy soul, upon Him Who is the Best-Beloved of all creation, and say:
O Thou Who art my God, my King, my Friend, and the Beloved of my heart and soul! How can I, incapable as I am, ever possibly thank Thee the way Thou deservest to be thanked? I was immersed in a sea of heedlessness and ignorance; the tongue of Thy grace summoned me, and the hand of Thy bounty took hold of me. O my God! My heedlessness hath assumed such grievous proportions that it hath deprived me of the cooling river of certitude, and led me instead unto the festering and fetid waters of idle fancy.  I have neglected Thy remembrance, yet Thou hast not neglected me. I had yet to be set ablaze with the flame of Thy love, but the fire of Thy tender mercies burned brightly nonetheless. How can I befittingly set my face towards Thee, and what tongue can adequately voice my supplications to Thee? Shame and agitation have pervaded my entire being, and brought on me despair from every side.
Yet, O my God—Thou Who art my Aim and my Lord—I have heard that Thou hast decreed that this is the day in which, if a man but once crieth out with sincerity the words, “Reveal Thyself unto me, O my Lord!”,  he will hear from the Kingdom of utterance, “Behold, and thou shalt see Me.”  In truth, the magnitude of this day is clear and apparent in these blessed and exalted words. Thou hast likewise declared that if a man hath, from the beginning that hath no beginning, failed to perform so much as a single goodly deed, it would nevertheless be possible for him in this day to make amends, inasmuch as the ocean of Thy pardon can be readily discerned in the midst of creation, and the firmament of Thy forgiveness is raised high. I entreat Thee, by the sanctity of this blessed day—the day which is the source and the dawning-place of all others—to aid me to do that which is pleasing unto Thee, and to attire me with the ornament of Thine acceptance.
O my Lord! I am a wretched creature, and with Thee are oceans of riches. I am woefully ignorant, and with Thee are the treasuries of knowledge and understanding. I am one far removed, and Thou art the Almighty, the Most Exalted, the Ever-Near.
 The phrase translated here as “festering and fetid waters” (máʼ-i-ṣadíd) is, in the original, identical to the wording used in Qurʼán 14:16.
 Qurʼán 7:143. This pertains to the Qurʼánic portrayal of Moses’s encounter with God on Mount Sinai, in which Moses says to God, “Reveal Thyself unto me, O my Lord, that I may behold Thee” (rabbi, ariní anẓur ílayk!). To this plea, God replies, “Thou shalt never see Me” (lan tarání). Refer to note 3 for more.
 The implications of this passage, especially those of this new reply from heaven (unẓur, tarání), are immense. Among other things, it may suggest that this day, marked by the advent of Baháʼuʼlláh, represents the first era in which humanity has been able to adequately appreciate the station of the Manifestation of God. It is in this light that we can understand the incisive comments of the celebrated and martyred Baháʼí philosopher, Dr. ʻAlí-Murád Dávúdí (Ulúhíyyat va Maẓharíyyat, 35–38), on this particular prayer, when he astutely observed that the key difference between the experience of Moses and that of the contemporary (if ordinary) suppliant as depicted in this prayer is that Moses yearned to behold the Essence of God—a feat impossible even for a Manifestation—whereas the suppliant mentioned here does have the ability, contingent on their spiritual perceptiveness, to recognize God in His Manifestation. The point is that the discrepant results of such entreaties stem from both the suppliant’s level of spiritual insight and also the nature of what is besought, with the former certainly influencing their conception of the latter. Essentially, if a person wishes to see God today, they can do this by recognizing the Manifestation—but if they fail to realize that the Manifestation represents the greatest extent to which they can ever comprehend God, then they will never see Him.
A typed version of the complete Persian and Arabic text of this prayer appears below.