" ... cleanse the eye of thine heart from the things of the world, that thou mayest realize the infinitude of divine knowledge ..."

"Dear friend! Now when the light of God’s everlasting Morn is breaking; when the radiance of His holy words: “God is the light of the heavens and of the earth” 5 is shedding illumination upon all mankind; when the inviolability of His tabernacle is being proclaimed by His sacred utterance: “God hath willed to perfect His light;” 6 and the Hand of omnipotence, bearing His testimony: “In His grasp He holdeth the kingdom of all things,” is being outstretched unto all the peoples and kindreds of the earth; it behooveth us to gird up the loins of endeavour, that haply, by the grace and bounty of God, we may enter the celestial City: “Verily, we are God’s,” and abide within the exalted habitation: “And unto Him we do return.” It is incumbent upon thee, by the permission of God, to cleanse the eye of thine heart from the things of the world, that thou mayest realize the infinitude of divine knowledge, and mayest behold Truth so clearly that thou wilt need no proof to demonstrate His reality, nor any evidence to bear witness unto His testimony."

-Bahá'u'lláh, The Kitáb-i-Íqán, pp. 90-91

5. Qur’án 24:35. 
6. Qur’án 9:33.