Charles Spurgeon Commentary Acts 2:16-21

"but this is that which hath been spoken through the prophet Joel: And it shall be in the last days, saith God, I will pour forth 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: Yea and on my servants and on my handmaidens in those days Will I pour forth of my Spirit; and they shall prophesy. And I will show wonders in the heaven above, And signs on the earth beneath; Blood, and fire, and vapor of smoke: The sun shall be turned into darkness, And the moon into blood, Before the day of the Lord come, That great and notable [day]. And it shall be, that whosoever shall call on the name of the Lord shall be saved." — Acts 2:16-21 (ASV)

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, and I will shew wonders in heaven above, and signs in the earth beneath; blood, and fire, and vapor of smoke: the sun shall be turned into darkness, and the moon into blood, before that great and notable day of the Lord come: and it shall come to pass, that whosoever shall call on the name of the Lord shall be saved.

Peter was speaking to a Jewish audience, so he began by quoting from the Old Testament. He was wise to win their attention by a long passage out of one of their own prophets. Now he comes nearer to his main point: