The promise
Around 1000 BC, King David wrote a psalm full of joy, and it ends with a promise about death itself:
"Therefore my heart hath been glad, and my tongue hath rejoiced: moreover, my flesh also shall rest in hope. Because thou wilt not leave my soul in hell; nor wilt thou give thy holy one to see corruption."
Psalm 15:9 to 10 (16:9 to 10 in most Bibles) ยท David, around 1000 BC
"Hell" here means the grave, the place of the dead. "Corruption" means decay. The holy one would die, but not be left in the grave, and his body would not rot.
David's tomb
Here's the problem. David died, and was buried in Jerusalem, and his body decayed like anyone else's.
Fifty days after the crucifixion, Peter stood up in Jerusalem and pointed it out to the crowd:
"Ye men, brethren, let me freely speak to you of the patriarch, David, that he died, and was buried: and his sepulchre is with us to this present day."
Acts 2:29
Everyone listening knew where David's tomb was. It was right there in the city.
So who was it about?
Peter gave the answer:
"Whereas, therefore, he was a prophet... Foreseeing he spoke of the resurrection of Christ, for neither was he left in hell, neither did his flesh see corruption. This Jesus hath God raised up again, whereof we are all witnesses."
Acts 2:30 to 32
David's tomb had David in it. Jesus' tomb, in the same city, was empty.
Paul made the same point years later: "David... slept: and was laid unto his fathers, and saw corruption. But he whom God hath raised from the dead, saw no corruption" (Acts 13:36 to 37).
Three days
Decay sets in fast. When Jesus came to the tomb of Lazarus, Martha warned him: "by this time he stinketh, for he is now of four days" (John 11:39).
Jesus was raised on the third day. Before corruption could touch him.
Why this is a big deal
David wrote about a holy one who would die but not decay, a thousand years before it happened. His own tomb proved he wasn't talking about himself.
Peter stood in the city with both tombs in it, the full one and the empty one, and told Jerusalem which one the psalm was about.