What follows is my provisional translation (in other words, not official or authorized; see here for more) of a passage from a Tablet of Bahá’u’lláh, the original text of which appears in Payk-i-Rástán, pp. 179–180.
Thou must, under all conditions, fix thy gaze upon and hold fast to this blessed verse revealed in the Qur’án: “He doeth what He willeth and ordaineth what He pleaseth.”[1] In truth, this blessed verse hath ever been, and continueth to be, an army of divine protection. Train the faithful through this exalted utterance, and guard them against things that neither nourish nor profit.[2] The words “He doeth what He willeth” are a most great sign, and a teacher virtuous and wise. Blessed is the soul that truly cleaveth thereunto. Such a one is, in all circumstances, protected and preserved.
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[1] This exact construction does not seem to occur anywhere in the Qur’án, but there are verses that include either of the two clauses that compose it. For examples, see Qur’án 2:253, 3:40, 14:27, 22:14, and 22:18.
[2] cf. Qur’án 88:7.
A typescript of the original Persian and Arabic text of this passage appears below (all punctuation and short vowel marks mine).