I will not leave you comfortless: I will come to you.

Jesus comforted His disciples with the promise that He would never leave them nor forsake them. Though He would die and be buried, on the third day He would rise again.

"To whom also he shewed himself alive after his passion by many infallible proofs, being seen of them forty days, and speaking of the things pertaining to the kingdom of God:" - Acts 1:3

When He departed from His disciples up to heaven forty days after His resurrection, He reassured them again that He would come to them in an even greater capacity, in “not many days hence.”

"And, being assembled together with them, commanded them that they should not depart from Jerusalem, but wait for the promise of the Father, which, saith he, ye have heard of me. For John truly baptized with water; but ye shall be baptized with the Holy Ghost not many days hence." - Acts 1:4-5

"And when he had spoken these things, while they beheld, he was taken up; and a cloud received him out of their sight." - Acts 1:9

On the Day of Pentecost, Jesus came to His disciples as He said He would. The Father that was in Christ doing the works, would now dwell in His disciples.

Before when Philip had asked Jesus to show them the Father,

"Jesus saith unto him, Have I been so long time with you, and yet hast thou not known me, Philip? he that hath seen me hath seen the Father; and how sayest thou then, Shew us the Father? Believest thou not that I am in the Father, and the Father in me? the words that I speak unto you I speak not of myself: but the Father that dwelleth in me, he doeth the works." - John 14:9-10

"If ye love me, keep my commandments. And I will pray the Father, and he shall give you another Comforter, that he may abide with you for ever; 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." - John 14:15-17

"I will not leave you comfortless: I will come to you." - John 14:18