“But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you.” (St. John 14:26)
"The passage in the Gospel of St. John 14:26, is a reference to the Revelation of Bahá’u’lláh, through Whose coming this prophecy was fulfilled." (From a letter written on behalf of Shoghi Effendi to an individual believer, April 21, 1939; Lights of Guidance, p. 478)