Holy Ghost Manifested to the Disciples on the Day of Pentecost

When the people at Pentecost exclaimed, 'Men and brethren, what shall we do?', Peter told them to repent and be baptized in the name of Jesus Christ for the remission of sins, and they should receive the gift of the Holy Ghost. The promise was to them, their children, and all who were afar off. This manifestation of the Holy Ghost upon the apostles and those with them aligns with Joel's prophecy of the Spirit being poured out upon all flesh.

Fuller account of this event (as retold in Acts 2:1-41, The Church of Jesus Christ of Latter-day Saints):

And when the day of Pentecost was fully come, they were all with one accord in one place. And suddenly there came a sound from heaven as of a rushing mighty wind, and it filled all the house where they were sitting. And there appeared unto them cloven tongues like as of fire, and it sat upon each of them. And they were all filled with the Holy Ghost, and began to speak with other tongues, as the Spirit gave them utterance. And there were dwelling at Jerusalem Jews, devout men, out of every nation under heaven. Now when this was noised abroad, the multitude came together, and were confounded, because that every man heard them speak in his own language. And they were all amazed and marvelled, saying one to another, Behold, are not all these which speak Galilæans? And how hear we every man in our own tongue, wherein we were born? Others mocking said, These men are full of new wine. But Peter, standing up with the eleven, lifted up his voice, and said unto them, Ye men of Judæa, and all ye that dwell at Jerusalem, be this known unto you, and hearken to my words: For these are not drunken, as ye suppose, seeing it is but the third hour of the day. But this is that which was spoken by the prophet Joel; 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: And on my servants and on my handmaidens I will pour out in those days of my Spirit; and they shall prophesy: Now when they heard this, they were pricked in their heart, and said unto Peter and to the rest of the apostles, Men and brethren, what shall we do? 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. And with many other words did he testify and exhort, saying, Save yourselves from this untoward generation. Then they that gladly received his word were baptized: and the same day there were added unto them about three thousand souls.