John 14

At the very hour in which the Savior was about to take upon him the sins and afflictions of all men -

"Which suffering caused myself, even God, the greatest of all, to tremble because of pain, and to bleed at every pore, and to suffer both body and spirit..." (Doctrine and Covenants | Section 19:18)

He warns His disciples -

"Hereafter I will not talk much with you: for the prince of this world cometh, and hath nothing in me." (New Testament | John 14:30)

Or as the Prophet Joseph Smith translated -

"Hereafter I will not talk much with you; for the prince of darkness, who is of this world, cometh, but hath no power over me, but he hath power over you." (JST)

Thus he teaches them -

"Peace I leave with you, my peace I give unto you: not as the world giveth, give I unto you. Let not your heart be troubled, neither let it be afraid." (New Testament | John 14:27)

And how would He do this?

"I will pray the Father, and he shall give you another Comforter, that he may abide with you for ever;
17 Even the Spirit of truth; whom the world cannot receive, because it seeth him not, neither knoweth him: but ye know him; for he dwelleth with you, and shall be in you." (New Testament | John 14:16 - 17)

For -

"...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." (New Testament | John 14:26)

This so called Gift of the Holy Ghost, is only available to -

He that hath my commandments, and keepeth them, he it is that loveth me: and he that loveth me shall be loved of my Father..." (New Testament | John 14:21)