Albert Barnes Commentary Acts 2:32

"This Jesus did God raise up, whereof we all are witnesses." — Acts 2:32 (ASV)

This Jesus. Peter, having shown that it was predicted that the Messiah would rise, now affirms that this happened in the case of Jesus. If it were a matter of prophecy, all objection to the truth of the doctrine was removed, and the only question was whether there was evidence that this had occurred. Peter now presents this proof, offering his own testimony and that of his brothers to the truth of this great and glorious fact.

We all are witnesses. It seems probable that Peter refers here to all one hundred and twenty who were present and who were ready to attest to it in any way. The point to be proved was that Jesus was seen alive after he had been put to death. The apostles were appointed to bear witness to this. And we are told by Paul (1 Corinthians 15:6) that he was seen by more than five hundred brothers (that is, Christians) at one time. The one hundred and twenty assembled on this occasion were undoubtedly part of that number and were ready to attest to this. This was the proof that Peter presented, and the strength of this proof was, and should have been, perfectly irresistible.

1. They had seen him themselves. They did not conjecture it or reason about it; instead, they had the evidence on which people act every day, and which must be regarded as satisfactory—the evidence of their own senses.
2. The number was such that they could not be deceived. If one hundred and twenty persons could not prove a plain matter of fact, nothing could be established by testimony; there could be no way of arriving at any facts.
3. The point to be established was a plain matter. It was not that they saw him rise; they never pretended that. Impostors would have done so. Instead, it was that they saw him, talked, walked, ate, and drank with him, being alive AFTER he had been crucified. The fact of his death was a matter of Jewish record, and no one called it into question. The only fact Christianity needed to establish was that he was seen alive afterwards; and this was attested by many witnesses.
4. They had no interest in deceiving the world in this matter. There was no prospect of pleasure, wealth, or honor in doing it.
5. They now offered themselves as ready to endure any sufferings, or to die, as a testament to the truth of this event.