1. The Holy Spirit came to those who believe in Jesus as the Christ (Pentecost, Lev 23:16)
    Joel 2:28, 32, Acts 2:16-17, 21, Acts 5:29-32, Eph 3:4-6

On the 50th day after the Exodus, the Israelites harvested grain. They offered a grain offering to God with the grain. (Lev 23:16)

Lev 23:16 Even unto the morrow after the seventh sabbath shall ye number fifty days; and ye shall offer a new meat offering unto the Lord.

In the Old Testament it was foretold that God would pour out the Holy Spirit on those who call on the name of the Lord. (Joel 2:28,32)

Joel 2:28 And it shall come to pass afterward, that I will pour out my spirit upon all flesh; and your sons and your daughters shall prophesy, your old men shall dream dreams, your young men shall see visions:
32 And it shall come to pass, that whosoever shall call on the name of the Lord shall be delivered: for in mount Zion and in Jerusalem shall be deliverance, as the Lord hath said, and in the remnant whom the Lord shall call.

50 days after Jesus was resurrected, the Holy Spirit prophesied in the Old Testament came upon those who believed in Jesus as the Christ. (Acts 2:16-17,21, Acts 5:29-32)

Acts 2:16 But this is that which was spoken by the prophet Joel;
17 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:
21 And it shall come to pass, that whosoever shall call on the name of the Lord shall be saved.

Acts 5:29 Then Peter and the other apostles answered and said, We ought to obey God rather than men.
30 The God of our fathers raised up Jesus, whom ye slew and hanged on a tree.
31 Him hath God exalted with his right hand to be a Prince and a Saviour, for to give repentance to Israel, and forgiveness of sins.
32 And we are his witnesses of these things; and so is also the Holy Ghost, whom God hath given to them that obey him.