At the first Pentecost, Peter said of the Spirit, “this is that which was spoken by the prophet Joel.” This is that: the age of the Spirit has arrived. This is that: “I will remove the heart of stone from your flesh and give you a heart of flesh. I will put My Spirit within you and cause you to walk in My statutes…” Ezekiel 36:26-27. This is that: “‘I will put My law within them, and on their heart I will write it; and I will be their God, and they shall be My people.’” Jeremiah 31:33. This is that: the Spirit is also for gentiles, women, slaves and nobodies. This is that: power to be a witness, Acts 1:8. This is that: the Spirit “cleansing the heart by faith” Acts 15:9.
“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”. Acts 2:16-18 (KJV)