What follows is my provisional translation (in other words, not official or authorized; see here for more) of a Tablet of ʻAbduʼl-Bahá, the original text of which is published in Yádnámiy-i-Miṣbáḥ-i-Munír, p. 318. According to the heading which precedes this Tablet in INBA 87:376, it was addressed to a Baháʼí by the name of Áqá Mírzá Muḥammad-Ḥusayn Nivísandih in Shiraz, and it was delivered to him through an eminent Baháʼí of that city known as Bashír-i-Iláhí.
He is God
O thou who art led aright by the light of guidance! Jináb-i-Áqá Muḥammad-Ḥasan truly conferred spiritual existence and eternal life. He benefited from the breaths of the Holy Spirit, and breathed them into thy heart and soul. His conscience became a heavenly rose-garden, and his mind the throne of the Glorious King.
The station of assurance is above that of faith, and “the truth of certitude” transcendeth “the knowledge of certitude.” Now that thou hast quaffed from the wellspring of certitude, thou wilt undoubtedly reach the truth of certitude through the limitless outpourings of God’s grace, that thereby thou mayest become the embodiment of endless bounties in this world and the next.
Upon thee be the glory of the All-Glorious.
 These are all references to the three levels of certitude in the Islamic mystical tradition—ʻilmu’l-yaqín (“the knowledge of certitude”), ʻaynu’l-yaqín (“the eye of certitude”), and ḥaqqu’l-yaqín (“the truth of certitude”)—to which Baháʼuʼlláh alludes in some of His Writings. In the Kitáb-i-Íqán, for instance, He refers to manáhij-i-ʻilmu’l-yaqín (translated by Shoghi Effendi as “the Path of Positive Knowledge”), and shortly thereafter to marátib-i-ʻaynu’l-yaqín va ḥaqqu’l-yaqín va núru’l-yaqín (all rendered by Shoghi Effendi as “the stations of absolute certitude,” with the last term in the series—literally, “the light of certitude”—apparently being a new concept). There is also another Tablet of Baháʼuʼlláh, an authorized English translation of which has been published as selection no. 6 in Call of the Divine Beloved, in which He characterizes these levels of certitude as “the inner and outer journeys of the soul”; see here for the relevant passage. Furthermore, beyond this Tablet, ʻAbdu’l-Bahá has also discussed these concepts with reference to Abraham in a Tablet to Ustád Ḥusayn Khayyát, an excerpt from which is published in Máʼidiy-i-Ásmání, vol. 9, pp. 105–06, and an Arabic prayer published in Yádnámiy-i-Miṣbáḥ-i-Munír, p. 319. A provisional rendering of the former by Khazeh Fananapazir is available online here. The latter has yet to be translated into English.
 ʻAbdu’l-Bahá is employing a double entendre that is inevitably lost in translation. Within the context of Islamic mysticism, the word ʻayn in the term ʻaynu’l-yaqín means “eye,” but it can also denote a source of water, and this is the sense in which ʻAbdu’l-Bahá is using it here; hence, His use of the verb “to quaff” (núshídan).
A typescript of the original Persian text of this Tablet appears below.