“He is the First and the Last; the Seen and the Hidden; and He knoweth all things!”

"I shall restate here My theme, that perchance this may assist thee in recognizing thy Creator. Know thou that God—exalted and glorified be He—doth in no wise manifest His inmost Essence and Reality. From time immemorial He hath been veiled in the eternity of His Essence and concealed in the infinitude of His own Being. And when He purposed to manifest His beauty in the kingdom of names and to reveal His glory in the realm of attributes, He brought forth His Prophets from the invisible plane to the visible, that His name “the Manifest” might be distinguished from “the Hidden” and His name “the Last” might be discerned from “the First”, and that there may be fulfilled the words: “He is the First and the Last; the Seen and the Hidden; and He knoweth all things!” 5 Thus hath He revealed these most excellent names and most exalted words in the Manifestations of His Self and the Mirrors of His Being."

-Bahá'u'lláh, Gems of Divine Mysteries (Javáhiru’l-Asrár), pp. 34-35

 5. Qur’án 57:3.