And we are witnesses of all things which he did both in the land of the Jews, and in Jerusalem; whom they slew and hanged on a tree: We are witnesses of all - In this speech St. Peter may refer, not only to the twelve apostles, but to the six brethren whom he had brought with him.
Whom they slew - As the truth of the resurrection must depend on the reality of the death of Christ, it was necessary that this should be stated, and shown to rest on the most indubitable evidence.