And in the fourth Gospel, according to John, it is recorded: “But when the Comforter is come, whom I will send unto you from the Father, even the Spirit of truth, which proceedeth from the Father, he shall testify of me: and ye also shall bear witness.” And elsewhere He saith: “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.” And: “But now I go my way to him that sent me; and none of you asketh me, Whither goest thou? But because I have said these things unto you...” And yet again: “Nevertheless I tell you the truth: It is expedient for you that I go away: for if I go not away, the Comforter will not come unto you; but if I depart, I will send him unto you.” And: “Howbeit when he, the Spirit of truth, is come, he will guide you into all truth: for he shall not speak of himself; but whatsoever he shall hear, that shall he speak: and he will show you things to come.”
Bahá'u'lláh