Jesus said,

"And, behold, I send the promise of my Father upon you: but tarry ye in the city of Jerusalem, until ye be endued with power from on high." - Luke 24:49

What is the promise of the Father?

"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

Joel prophesied of the promise of the Father. He would pour out of His Spirit on all flesh.

"And it shall come to pass in the last days, saith God, I will pour out of my Spirit upon all flesh: and your sons and your daughters shall prophesy, and your young men shall see visions, and your old men shall dream dreams:" - Acts 2:17

Jesus said,

"He that believeth on me, as the scripture hath said, out of his belly shall flow rivers of living water. (But this spake he of the Spirit, which they that believe on him should receive: for the Holy Ghost was not yet given; because that Jesus was not yet glorified.)" - John 7:38-39

Since the promise of the Father is the Holy Ghost, how would the Father’s Spirit be flowing from the belly of Jesus? Because Jesus is the Father robed in flesh.

"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 14:10

The promise of the Father, His Spirit, which is the Holy Ghost, was first received on the Day of Pentecost. Jesus poured out of His Spirit on the 120 disciples which were gathered in the upper room.

"At that day ye shall know that I am in my Father, and ye in me, and I in you." - John 14:20

Peter preached,

"Therefore being by the right hand of God exalted, and having received of the Father the promise of the Holy Ghost, he hath shed forth this, which ye now see and hear." - Acts 2:33

"And they were all filled with the Holy Ghost, and began to speak with other tongues, as the Spirit gave them utterance." - Acts 2:4

Jesus prayed for His disciples, as well as for those that would hear their message,

"That they all may be one; as thou, Father, art in me, and I in thee, that they also may be one in us: that the world may believe that thou hast sent me." - John 17:21

What is the message preached of the promise of the Father, the Holy Ghost?

"Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost. For the promise is unto you, and to your children, and to all that are afar off, even as many as the Lord our God shall call." - Acts 2:38-39

"Then they that gladly received his word were baptized: and the same day there were added unto them about three thousand souls." - Acts 2:41